RNA recognition motif (RRM) superfamily; RRM, also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), is a highly abundant domain in eukaryotes found in proteins involved in post-transcriptional gene expression processes including mRNA and rRNA processing, RNA export, and RNA stability. This domain is 90 amino acids in length and consists of a four-stranded beta-sheet packed against two alpha-helices. RRM usually interacts with ssRNA, but is also known to interact with ssDNA as well as proteins. RRM binds a variable number of nucleotides, ranging from two to eight. The active site includes three aromatic side-chains located within the conserved RNP1 and RNP2 motifs of the domain. The RRM domain is found in a variety heterogeneous nuclear ribonucleoproteins (hnRNPs), proteins implicated in regulation of alternative splicing, and protein components of small nuclear ribonucleoproteins (snRNPs).

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1934786259   1 MMDETEIGSCFGRYGSVKEVKIITNRTGVSKGYGFVSFVNDVDVQKIVGSQIHFHGKKLKLGPAIRK 67
Cdd:cd12672    16 RMDENEIRSFFARYGSVKEVKIITDRTGVSKGYGFVSFYDDVDIQKIVESQINFHGKKLKLGPAIRK 82

RNA recognition motif (RRM) found in vertebrate deleted in azoospermia-like (DAZL) proteins; This subgroup corresponds to the RRM of DAZL, also termed SPGY-like-autosomal, encoded by the autosomal homolog of DAZ gene, DAZL. It is ancestral to the deleted in azoospermia (DAZ) protein. DAZL is germ-cell-specific RNA-binding protein that contains a RNA recognition motif (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a DAZ motif, a protein-protein interaction domain. Although their specific biochemical functions remain to be investigated, DAZL proteins may interact with poly(A)-binding proteins (PABPs), and act as translational activators of specific mRNAs during gametogenesis.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1934786259   1 MMDETEIGSCFGRYGSVKEVKIITNRTGVSKGYGFVSFVNDVDVQKIVGSQIHFHGKKLKLGPAIRK 67
Cdd:cd12672    16 RMDENEIRSFFARYGSVKEVKIITDRTGVSKGYGFVSFYDDVDIQKIVESQINFHGKKLKLGPAIRK 82

RNA recognition motif (RRM) domain [Translation, ribosomal structure and biogenesis];

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKIV----GSQihFHGKKLKLGPA 64
Cdd:COG0724    13 VTEEDLRELFSEYGEVTSVKLITDReTGRSRGFGFVEMPDDEEAQAAIealnGAE--LMGRTLKVNEA 78

polyadenylate binding protein, human types 1, 2, 3, 4 family; These eukaryotic proteins recognize the poly-A of mRNA and consists of four tandem RNA recognition domains at the N-terminus (rrm: pfam00076) followed by a PABP-specific domain (pfam00658) at the C-terminus. The protein is involved in the transport of mRNA's from the nucleus to the cytoplasm. There are four paralogs in Homo sapiens which are expressed in testis, platelets, broadly expressed and of unknown tissue range.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1934786259   3 DETEIGSCFGRYGSVKEVKIITNRTGVSKGYGFVSFVNDVDVQKIVgSQIH---FHGKKLKLGPAIRKQKLCArHVQprp 79
Cdd:TIGR01628 298 TDEKLRELFSECGEITSAKVMLDEKGVSRGFGFVCFSNPEEANRAV-TEMHgrmLGGKPLYVALAQRKEQRRA-HLQ--- 372

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1934786259  80 lvvnppppPQF-QNVWRNPNTetylqPQITPNPVTQHVQAYsaYPHSPGQVITGcQLLVYNYQE---YPTYPDSAFQVTT 155
Cdd:TIGR01628 373 --------DQFmQLQPRMRQL-----PMGSPMGGAMGQPPY--YGQGPQQQFNG-QPLGWPRMSmmpTPMGPGGPLRPNG 436

                         170       180       190       200
                  ....*....|....*....|....*....|....*....|...
gi 1934786259 156 gyqLPVYNYQPFPayprSPFQVTAGYQLPVYNYQAFPAYPNSP 198
Cdd:TIGR01628 437 ---LAPMNAVRAP----SRNAQNAAQKPPMQPVMYPPNYQSLP 472

glycine-rich RNA-binding protein 4; Provisional

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1934786259   3 DETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFvNDVDVQKIVGSQI---HFHGKKLKLGPA 64
Cdd:PLN03134   47 DDASLRDAFAHFGDVVDAKVIVDReTGRSRGFGFVNF-NDEGAATAAISEMdgkELNGRHIRVNPA 111

RNA recognition motif (RRM) found in vertebrate deleted in azoospermia-like (DAZL) proteins; This subgroup corresponds to the RRM of DAZL, also termed SPGY-like-autosomal, encoded by the autosomal homolog of DAZ gene, DAZL. It is ancestral to the deleted in azoospermia (DAZ) protein. DAZL is germ-cell-specific RNA-binding protein that contains a RNA recognition motif (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a DAZ motif, a protein-protein interaction domain. Although their specific biochemical functions remain to be investigated, DAZL proteins may interact with poly(A)-binding proteins (PABPs), and act as translational activators of specific mRNAs during gametogenesis.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1934786259   1 MMDETEIGSCFGRYGSVKEVKIITNRTGVSKGYGFVSFVNDVDVQKIVGSQIHFHGKKLKLGPAIRK 67
Cdd:cd12672    16 RMDENEIRSFFARYGSVKEVKIITDRTGVSKGYGFVSFYDDVDIQKIVESQINFHGKKLKLGPAIRK 82

RNA recognition motif (RRM) found in protein BOULE; This subgroup corresponds to the RRM of BOULE, the founder member of the human DAZ gene family. Invertebrates contain a single BOULE, while vertebrates, other than catarrhine primates, possess both BOULE and DAZL genes. The catarrhine primates possess BOULE, DAZL, and DAZ genes. BOULE encodes an RNA-binding protein containing an RNA recognition motif (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a single copy of the DAZ motif. Although its specific biochemical functions remains to be investigated, BOULE protein may interact with poly(A)-binding proteins (PABPs), and act as translational activators of specific mRNAs during gametogenesis.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1934786259   3 DETEIGSCFGRYGSVKEVKIITNRTGVSKGYGFVSFVNDVDVQKIV--GSQIHFHGKKLKLGPAIRK 67
Cdd:cd12673    15 NENDLRKFFAQYGSVKEVKIVNDRAGVSKGYGFITFETQEDAQKILqeAEKLNYKDKKLNIGPAIRK 81

RNA recognition motif (RRM) superfamily; RRM, also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), is a highly abundant domain in eukaryotes found in proteins involved in post-transcriptional gene expression processes including mRNA and rRNA processing, RNA export, and RNA stability. This domain is 90 amino acids in length and consists of a four-stranded beta-sheet packed against two alpha-helices. RRM usually interacts with ssRNA, but is also known to interact with ssDNA as well as proteins. RRM binds a variable number of nucleotides, ranging from two to eight. The active site includes three aromatic side-chains located within the conserved RNP1 and RNP2 motifs of the domain. The RRM domain is found in a variety heterogeneous nuclear ribonucleoproteins (hnRNPs), proteins implicated in regulation of alternative splicing, and protein components of small nuclear ribonucleoproteins (snRNPs).

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNRTGVSKGYGFVSFVNDVDVQKIV--GSQIHFHGKKLKL 61
Cdd:cd00590    10 TTEEDLRELFSKFGEVVSVRIVRDRDGKSKGFAFVEFESPEDAEKALeaLNGTELGGRPLKV 71

RNA recognition motif 3 (RRM3) found found in type I polyadenylate-binding proteins; This subfamily corresponds to the RRM3 of type I poly(A)-binding proteins (PABPs), highly conserved proteins that bind to the poly(A) tail present at the 3' ends of most eukaryotic mRNAs. They have been implicated in the regulation of poly(A) tail length during the polyadenylation reaction, translation initiation, mRNA stabilization by influencing the rate of deadenylation and inhibition of mRNA decapping. The family represents type I polyadenylate-binding proteins (PABPs), including polyadenylate-binding protein 1 (PABP-1 or PABPC1), polyadenylate-binding protein 3 (PABP-3 or PABPC3), polyadenylate-binding protein 4 (PABP-4 or APP-1 or iPABP), polyadenylate-binding protein 5 (PABP-5 or PABPC5), polyadenylate-binding protein 1-like (PABP-1-like or PABPC1L), polyadenylate-binding protein 1-like 2 (PABPC1L2 or RBM32), polyadenylate-binding protein 4-like (PABP-4-like or PABPC4L), yeast polyadenylate-binding protein, cytoplasmic and nuclear (PABP or ACBP-67), and similar proteins. PABP-1 is an ubiquitously expressed multifunctional protein that may play a role in 3' end formation of mRNA, translation initiation, mRNA stabilization, protection of poly(A) from nuclease activity, mRNA deadenylation, inhibition of mRNA decapping, and mRNP maturation. Although PABP-1 is thought to be a cytoplasmic protein, it is also found in the nucleus. PABP-1 may be involved in nucleocytoplasmic trafficking and utilization of mRNP particles. PABP-1 contains four copies of RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), a less well conserved linker region, and a proline-rich C-terminal conserved domain (CTD). PABP-3 is a testis-specific poly(A)-binding protein specifically expressed in round spermatids. It is mainly found in mammalian and may play an important role in the testis-specific regulation of mRNA homeostasis. PABP-3 shows significant sequence similarity to PABP-1. However, it binds to poly(A) with a lower affinity than PABP-1. PABP-1 possesses an A-rich sequence in its 5'-UTR and allows binding of PABP and blockage of translation of its own mRNA. In contrast, PABP-3 lacks the A-rich sequence in its 5'-UTR. PABP-4 is an inducible poly(A)-binding protein (iPABP) that is primarily localized to the cytoplasm. It shows significant sequence similarity to PABP-1 as well. The RNA binding properties of PABP-1 and PABP-4 appear to be identical. PABP-5 is encoded by PABPC5 gene within the X-specific subinterval, and expressed in fetal brain and in a range of adult tissues in mammalian, such as ovary and testis. It may play an important role in germ cell development. Moreover, unlike other PABPs, PABP-5 contains only four RRMs, but lacks both the linker region and the CTD. PABP-1-like and PABP-1-like 2 are the orthologs of PABP-1. PABP-4-like is the ortholog of PABP-5. Their cellular functions remain unclear. The family also includes the yeast PABP, a conserved poly(A) binding protein containing poly(A) tails that can be attached to the 3'-ends of mRNAs. The yeast PABP and its homologs may play important roles in the initiation of translation and in mRNA decay. Like vertebrate PABP-1, the yeast PABP contains four RRMs, a linker region, and a proline-rich CTD as well. The first two RRMs are mainly responsible for specific binding to poly(A). The proline-rich region may be involved in protein-protein interactions.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNRTGVSKGYGFVSFVNDVDVQKIV----GSQihFHGKKLKLGpaiRKQK 69
Cdd:cd12380    13 VDDDELKELFEKYGKITSAKVMKDDSGKSKGFGFVNFENHEAAQKAVeelnGKE--LNGKKLYVG---RAQK 79

RNA recognition motif 2 (RRM2) found in Nicotiana sylvestris chloroplastic 33 kDa ribonucleoprotein (NsCP33) and similar proteins; The family includes NsCP33, Arabidopsis thaliana chloroplastic 31 kDa ribonucleoprotein (CP31A) and mitochondrial glycine-rich RNA-binding protein 2 (AtGR-RBP2). NsCP33 may be involved in splicing and/or processing of chloroplast RNA's. AtCP31A, also called RNA-binding protein 1/2/3 (AtRBP33), or RNA-binding protein CP31A, or RNA-binding protein RNP-T, or RNA-binding protein cp31, is required for specific RNA editing events in chloroplasts and stabilizes specific chloroplast mRNAs, as well as for normal chloroplast development under cold stress conditions by stabilizing transcripts of numerous mRNAs under these conditions. CP31A may modulate telomere replication through RNA binding domains. AtGR-RBP2, also called AtRBG2, or glycine-rich protein 2 (AtGRP2), or mitochondrial RNA-binding protein 1a (At-mRBP1a), plays a role in RNA transcription or processing during stress. It binds RNAs and DNAs sequence with a preference to single-stranded nucleic acids. AtGR-RBP2 displays strong affinity to poly(U) sequence. It exerts cold and freezing tolerance, probably by exhibiting an RNA chaperone activity during the cold and freezing adaptation process. Some members in this family contain two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). The model corresponds to the second RRM motif.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQK 46
Cdd:cd21608    11 TTEDDLRDLFSEFGEVESAKVITDReTGRSRGFGFVTFSTAEAAEA 56

RNA recognition motif 1 (RRM1) found in tRNA selenocysteine-associated protein 1 (SECp43) and similar proteins; This subfamily corresponds to the RRM1 in tRNA selenocysteine-associated protein 1 (SECp43), yeast negative growth regulatory protein NGR1 (RBP1), yeast protein NAM8, and similar proteins. SECp43 is an RNA-binding protein associated specifically with eukaryotic selenocysteine tRNA [tRNA(Sec)]. It may play an adaptor role in the mechanism of selenocysteine insertion. SECp43 is located primarily in the nucleus and contains two N-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a C-terminal polar/acidic region. Yeast proteins, NGR1 and NAM8, show high sequence similarity with SECp43. NGR1 is a putative glucose-repressible protein that binds both RNA and single-stranded DNA (ssDNA). It may function in regulating cell growth in early log phase, possibly through its participation in RNA metabolism. NGR1 contains three RRMs, two of which are followed by a glutamine-rich stretch that may be involved in transcriptional activity. In addition, NGR1 has an asparagine-rich region near the C-terminus which also harbors a methionine-rich region. NAM8 is a putative RNA-binding protein that acts as a suppressor of mitochondrial splicing deficiencies when overexpressed in yeast. It may be a non-essential component of the mitochondrial splicing machinery. NAM8 also contains three RRMs.

                          10        20        30
                  ....*....|....*....|....*....|....*....
gi 1934786259   2 MDETEIGSCFGRYG-SVKEVKIITNR-TGVSKGYGFVSF 38
Cdd:cd12344    11 MDEAYISSCFAKTGeEVVSVKIIRNKqTGKSAGYCFVEF 49

RNA recognition motif 2 (RRM2) found in squamous cell carcinoma antigen recognized by T-cells 3 (SART3) and similar proteins; This subfamily corresponds to the RRM2 of SART3, also termed Tat-interacting protein of 110 kDa (Tip110), is an RNA-binding protein expressed in the nucleus of the majority of proliferating cells, including normal cells and malignant cells, but not in normal tissues except for the testes and fetal liver. It is involved in the regulation of mRNA splicing probably via its complex formation with RNA-binding protein with a serine-rich domain (RNPS1), a pre-mRNA-splicing factor. SART3 has also been identified as a nuclear Tat-interacting protein that regulates Tat transactivation activity through direct interaction and functions as an important cellular factor for HIV-1 gene expression and viral replication. In addition, SART3 is required for U6 snRNP targeting to Cajal bodies. It binds specifically and directly to the U6 snRNA, interacts transiently with the U6 and U4/U6 snRNPs, and promotes the reassembly of U4/U6 snRNPs after splicing in vitro. SART3 contains an N-terminal half-a-tetratricopeptide repeat (HAT)-rich domain, a nuclearlocalization signal (NLS) domain, and two C-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*
gi 1934786259   4 ETEIGSCFGRYGSVKEVKIITNRTGVSKGYGFVSFVNDVDVQKIV 48
Cdd:cd12392    16 KEELEELFKQHGTVKDVRLVTYRNGKPKGLAYVEYENEADASQAV 60

RNA recognition motif 2 (RRM2) found in RNA-binding protein 28 (RBM28) and similar proteins; This subfamily corresponds to the RRM2 of RBM28 and Nop4p. RBM28 is a specific nucleolar component of the spliceosomal small nuclear ribonucleoproteins (snRNPs), possibly coordinating their transition through the nucleolus. It specifically associates with U1, U2, U4, U5, and U6 small nuclear RNAs (snRNAs), and may play a role in the maturation of both small nuclear and ribosomal RNAs. RBM28 has four RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and an extremely acidic region between RRM2 and RRM3. The family also includes nucleolar protein 4 (Nop4p or Nop77p) encoded by YPL043W from Saccharomyces cerevisiae. It is an essential nucleolar protein involved in processing and maturation of 27S pre-rRNA and biogenesis of 60S ribosomal subunits. Nop4p also contains four RRMs.

                          10        20        30
                  ....*....|....*....|....*....|....*.
gi 1934786259  11 FGRYGSVKEVKIITNRTGVSKGYGFVSFVNDVDVQK 46
Cdd:cd12414    20 FSKFGKVLEVTIPKKPDGKLRGFAFVQFTNVADAAK 55

RNA recognition motif in nucleolar protein interacting with the FHA domain of pKI-67 (NIFK) and similar proteins; This subgroup corresponds to the RRM of NIFK and Nop15p. NIFK, also termed MKI67 FHA domain-interacting nucleolar phosphoprotein, or nucleolar phosphoprotein Nopp34, is a putative RNA-binding protein interacting with the forkhead associated (FHA) domain of pKi-67 antigen in a mitosis-specific and phosphorylation-dependent manner. It is nucleolar in interphase but associates with condensed mitotic chromosomes. This family also includes Saccharomyces cerevisiae YNL110C gene encoding ribosome biogenesis protein 15 (Nop15p), also termed nucleolar protein 15. Both, NIFK and Nop15p, contain an RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain).

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 1934786259   3 DETEIGSCFGRYGSVKEVKIITN-RTGVSKGYGFVSFVNDvDVQKIVGSQIH---FHGKKLK 60
Cdd:cd12307    12 YEPELRKYFSQFGTVTRLRLSRSkKTGKSKGYAFVEFEDP-EVAKIVAETMNnylLFERLLK 72

RNA recognition motif 2 (RRM2) found in tRNA selenocysteine-associated protein 1 (SECp43); This subgroup corresponds to the RRM2 of SECp43, an RNA-binding protein associated specifically with eukaryotic selenocysteine tRNA [tRNA(Sec)]. It may play an adaptor role in the mechanism of selenocysteine insertion. SECp43 is located primarily in the nucleus and contains two N-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a C-terminal polar/acidic region.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 1934786259  13 RYGSVKEVKIITNRTGVSKGYGFVSFVND-------VDVQKIVGsqihFHGKKLKLGPAIRK 67
Cdd:cd12612    25 RYPSCKGAKVVLDQLGNSRGYGFVRFSDEneqkralTECQGASG----LGGKPIRLSVAIPK 82

RNA recognition motif 2 (RRM2) found in yeast negative growth regulatory protein NGR1, yeast protein NAM8 and similar proteins; This subgroup corresponds to the RRM2 of NGR1 and NAM8. NGR1, also termed RNA-binding protein RBP1, is a putative glucose-repressible protein that binds both, RNA and single-stranded DNA (ssDNA), in yeast. It may function in regulating cell growth in early log phase, possibly through its participation in RNA metabolism. NGR1 contains two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), followed by a glutamine-rich stretch that may be involved in transcriptional activity. In addition, NGR1 has an asparagine-rich region near the carboxyl terminus which also harbors a methionine-rich region. The family also includes protein NAM8, which is a putative RNA-binding protein that acts as a suppressor of mitochondrial splicing deficiencies when overexpressed in yeast. It may be a non-essential component of the mitochondrial splicing machinery. Like NGR1, NAM8 contains two RRMs.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 1934786259  13 RYGSVKEVKIITN-RTGVSKGYGFVSFVNDVDVQKIVgsqIHFHGK 57
Cdd:cd12613    25 RFPSCKSAKIMTDpVTGVSRGYGFVRFSDENDQQRAL---IEMQGK 67

RNA recognition motif (RRM) found in cold inducible RNA binding protein (CIRBP), RNA binding motif protein 3 (RBM3) and similar proteins; This subfamily corresponds to the RRM domain of two structurally related heterogenous nuclear ribonucleoproteins, CIRBP (also termed CIRP or A18 hnRNP) and RBM3 (also termed RNPL), both of which belong to a highly conserved cold shock proteins family. The cold shock proteins can be induced after exposure to a moderate cold-shock and other cellular stresses such as UV radiation and hypoxia. CIRBP and RBM3 may function in posttranscriptional regulation of gene expression by binding to different transcripts, thus allowing the cell to response rapidly to environmental signals. However, the kinetics and degree of cold induction are different between CIRBP and RBM3. Tissue distribution of their expression is different. CIRBP and RBM3 may be differentially regulated under physiological and stress conditions and may play distinct roles in cold responses of cells. CIRBP, also termed glycine-rich RNA-binding protein CIRP, is localized in the nucleus and mediates the cold-induced suppression of cell cycle progression. CIRBP also binds DNA and possibly serves as a chaperone that assists in the folding/unfolding, assembly/disassembly and transport of various proteins. RBM3 may enhance global protein synthesis and the formation of active polysomes while reducing the levels of ribonucleoprotein complexes containing microRNAs. RBM3 may also serve to prevent the loss of muscle mass by its ability to decrease cell death. Furthermore, RBM3 may be essential for cell proliferation and mitosis. Both, CIRBP and RBM3, contain an N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), that is involved in RNA binding, and C-terminal glycine-rich domain (RGG motif) that probably enhances RNA-binding via protein-protein and/or protein-RNA interactions. Like CIRBP, RBM3 can also bind to both RNA and DNA via its RRM domain.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 1934786259   3 DETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKivgSQIHFHGKKLKlGPAIR 66
Cdd:cd12449    13 NEQSLEEVFSKYGQISEVVVVKDReTQRSRGFGFVTFENPDDAKD---AMMAMNGKSLD-GRQIR 73

RNA recognition motif (RRM) found in SRA stem-loop-interacting RNA-binding protein (SLIRP) and similar proteins; This subfamily corresponds to the RRM of SLIRP, a widely expressed small steroid receptor RNA activator (SRA) binding protein, which binds to STR7, a functional substructure of SRA. SLIRP is localized predominantly to the mitochondria and plays a key role in modulating several nuclear receptor (NR) pathways. It functions as a co-repressor to repress SRA-mediated nuclear receptor coactivation. It modulates SHARP- and SKIP-mediated co-regulation of NR activity. SLIRP contains an RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), which is required for SLIRP's corepression activities.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|...
gi 1934786259  11 FGRYGSVKEVKIITN-RTGVSKGYGFVSFVNDVDVQKIVGSQIH-FHGKKLKL 61
Cdd:cd12242    20 FSQFGKVKRCNLPFDkETGFHKGFGFVSFENEDGLRNALQKQKHiFEGNKVSV 72

RNA recognition motif 1 (RRM1) found in heterogeneous nuclear ribonucleoprotein hnRNP A and hnRNP D subfamilies and similar proteins; This subfamily corresponds to the RRM1 in the hnRNP A subfamily which includes hnRNP A0, hnRNP A1, hnRNP A2/B1, hnRNP A3 and similar proteins. hnRNP A0 is a low abundance hnRNP protein that has been implicated in mRNA stability in mammalian cells. hnRNP A1 is an abundant eukaryotic nuclear RNA-binding protein that may modulate splice site selection in pre-mRNA splicing. hnRNP A2/B1 is an RNA trafficking response element-binding protein that interacts with the hnRNP A2 response element (A2RE). hnRNP A3 is also a RNA trafficking response element-binding protein that participates in the trafficking of A2RE-containing RNA. The hnRNP A subfamily is characterized by two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), followed by a long glycine-rich region at the C-terminus. The hnRNP D subfamily includes hnRNP D0, hnRNP A/B, hnRNP DL and similar proteins. hnRNP D0 is a UUAG-specific nuclear RNA binding protein that may be involved in pre-mRNA splicing and telomere elongation. hnRNP A/B is an RNA unwinding protein with a high affinity for G- followed by U-rich regions. hnRNP A/B has also been identified as an APOBEC1-binding protein that interacts with apolipoprotein B (apoB) mRNA transcripts around the editing site and thus, plays an important role in apoB mRNA editing. hnRNP DL (or hnRNP D-like) is a dual functional protein that possesses DNA- and RNA-binding properties. It has been implicated in mRNA biogenesis at the transcriptional and post-transcriptional levels. All members in this subfamily contain two putative RRMs and a glycine- and tyrosine-rich C-terminus. The family also contains DAZAP1 (Deleted in azoospermia-associated protein 1), RNA-binding protein Musashi homolog Musashi-1, Musashi-2 and similar proteins. They all harbor two RRMs.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|
gi 1934786259  11 FGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKIVGSQIH-FHGKK 58
Cdd:cd12325    19 FSKYGEVVDCVVMKDPaTGRSRGFGFVTFKDPSSVDAVLAARPHtLDGRT 68

RNA recognition motif 3 (RRM3) found in CELF/Bruno-like family of RNA binding proteins CELF1, CELF2, CELF3, CELF4, CELF5, CELF6 and similar proteins; This subgroup corresponds to the RRM3 of the CUGBP1 and ETR-3-like factors (CELF) or BRUNOL (Bruno-like) proteins, a family of structurally related RNA-binding proteins involved in the regulation of pre-mRNA splicing in the nucleus and in the control of mRNA translation and deadenylation in the cytoplasm. The family contains six members: CELF-1 (also termed BRUNOL-2, or CUG-BP1, or NAPOR, or EDEN-BP), CELF-2 (also termed BRUNOL-3, or ETR-3, or CUG-BP2, or NAPOR-2), CELF-3 (also termed BRUNOL-1, or TNRC4, or ETR-1, or CAGH4, or ER DA4), CELF-4 (also termed BRUNOL-4), CELF-5 (also termed BRUNOL-5), CELF-6 (also termed BRUNOL-6). They all contain three highly conserved RNA recognition motifs (RRMs), also known as RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains): two consecutive RRMs (RRM1 and RRM2) situated in the N-terminal region followed by a linker region and the third RRM (RRM3) close to the C-terminus of the protein. The low sequence conservation of the linker region is highly suggestive of a large variety in the co-factors that associate with the various CELF family members. Based on both sequence similarity and function, the CELF family can be divided into two subfamilies, the first containing CELFs 1 and 2, and the second containing CELFs 3, 4, 5, and 6. The different CELF proteins may act through different sites on at least some substrates. Furthermore, CELF proteins may interact with each other in varying combinations to influence alternative splicing in different contexts.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKIV----GSQIhfHGKKLK 60
Cdd:cd12362    10 FTDQDLYQLFAPFGNVVSAKVFVDKnTGRSKGFGFVSYDNPLSAQAAIkamnGFQV--GGKRLK 71

RNA recognition motif 2 (RRM2) found in heterogeneous nuclear ribonucleoprotein A subfamily; This subfamily corresponds to the RRM2 of hnRNP A0, hnRNP A1, hnRNP A2/B1, hnRNP A3 and similar proteins. hnRNP A0 is a low abundance hnRNP protein that has been implicated in mRNA stability in mammalian cells. It has been identified as the substrate for MAPKAP-K2 and may be involved in the lipopolysaccharide (LPS)-induced post-transcriptional regulation of tumor necrosis factor-alpha (TNF-alpha), cyclooxygenase 2 (COX-2) and macrophage inflammatory protein 2 (MIP-2). hnRNP A1 is an abundant eukaryotic nuclear RNA-binding protein that may modulate splice site selection in pre-mRNA splicing. hnRNP A2/B1 is an RNA trafficking response element-binding protein that interacts with the hnRNP A2 response element (A2RE). Many mRNAs, such as myelin basic protein (MBP), myelin-associated oligodendrocytic basic protein (MOBP), carboxyanhydrase II (CAII), microtubule-associated protein tau, and amyloid precursor protein (APP) are trafficked by hnRNP A2/B1. hnRNP A3 is also a RNA trafficking response element-binding protein that participates in the trafficking of A2RE-containing RNA. The hnRNP A subfamily is characterized by two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), followed by a long glycine-rich region at the C-terminus.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|...
gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKIVGSQIH 53
Cdd:cd12328    11 VEEEDLREYFSQFGKVESVEIVTDKeTGKKRGFAFVTFDDHDSVDKIVLQKYH 63

RNA recognition motif 2 (RRM2) found in yeast nuclear polyadenylated RNA-binding protein 4 (Hrp1p or Nab4p) and similar proteins; This subfamily corresponds to the RRM1 of Hrp1p and similar proteins. Hrp1p or Nab4p, also termed cleavage factor IB (CFIB), is a sequence-specific trans-acting factor that is essential for mRNA 3'-end formation in yeast Saccharomyces cerevisiae. It can be UV cross-linked to RNA and specifically recognizes the (UA)6 RNA element required for both, the cleavage and poly(A) addition steps. Moreover, Hrp1p can shuttle between the nucleus and the cytoplasm, and play an additional role in the export of mRNAs to the cytoplasm. Hrp1p also interacts with Rna15p and Rna14p, two components of CF1A. In addition, Hrp1p functions as a factor directly involved in modulating the activity of the nonsense-mediated mRNA decay (NMD) pathway; it binds specifically to a downstream sequence element (DSE)-containing RNA and interacts with Upf1p, a component of the surveillance complex, further triggering the NMD pathway. Hrp1p contains two central RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and an arginine-glycine-rich region harboring repeats of the sequence RGGF/Y.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1934786259   3 DETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKIVGSQIH-FHGKKLKLGPAIRK 67
Cdd:cd12330    12 TEEEFKEYFEQFGTVVDAVVMLDHdTGRSRGFGFVTFDSESAVEKVLSKGFHeLGGKKVEVKRATPK 78

RNA recognition motif (RRM) found in RNA-binding protein with serine-rich domain 1 (RNPS1) and similar proteins; This subfamily corresponds to the RRM of RNPS1 and its eukaryotic homologs. RNPS1, also termed RNA-binding protein prevalent during the S phase, or SR-related protein LDC2, was originally characterized as a general pre-mRNA splicing activator, which activates both constitutive and alternative splicing of pre-mRNA in vitro.It has been identified as a protein component of the splicing-dependent mRNP complex, or exon-exon junction complex (EJC), and is directly involved in mRNA surveillance. Furthermore, RNPS1 is a splicing regulator whose activator function is controlled in part by CK2 (casein kinase II) protein kinase phosphorylation. It can also function as a squamous-cell carcinoma antigen recognized by T cells-3 (SART3)-binding protein, and is involved in the regulation of mRNA splicing. RNPS1 contains an N-terminal serine-rich (S) domain, a central RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and the C-terminal arginine/serine/proline-rich (RS/P) domain.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|...
gi 1934786259   5 TEIgscFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKIV----GSQI 52
Cdd:cd12365    16 KEI---FSVYGTVKNVDLPIDRePNLPRGYAYVEFESPEDAEKAIkhmdGGQI 65

RNA recognition motif 3 (RRM3) found in RNA-binding protein 28 (RBM28) and similar proteins; This subfamily corresponds to the RRM3 of RBM28 and Nop4p. RBM28 is a specific nucleolar component of the spliceosomal small nuclear ribonucleoproteins (snRNPs), possibly coordinating their transition through the nucleolus. It specifically associates with U1, U2, U4, U5, and U6 small nuclear RNAs (snRNAs), and may play a role in the maturation of both small nuclear and ribosomal RNAs. RBM28 has four RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and an extremely acidic region between RRM2 and RRM3. The family also includes nucleolar protein 4 (Nop4p or Nop77p) encoded by YPL043W from Saccharomyces cerevisiae. It is an essential nucleolar protein involved in processing and maturation of 27S pre-rRNA and biogenesis of 60S ribosomal subunits. Nop4p also contains four RRMs.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 1934786259   3 DETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKIV--------GSQIHFHGKKLKLGPA 64
Cdd:cd12415    13 TEEDLKEFFSKFGEVKYARIVLDKdTGHSKGTAFVQFKTKESADKCIeaandeseDGGLVLDGRKLIVSLA 83

RNA recognition motif 2 (RRM2) found in RNA-binding protein 34 (RBM34) and similar proteins; This subfamily corresponds to the RRM2 of RBM34, a putative RNA-binding protein containing two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). Although the function of RBM34 remains unclear currently, its RRM domains may participate in mRNA processing. RBM34 may act as an mRNA processing-related protein.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKivgsQIHFHGKKLKlGPAIR 66
Cdd:cd12395    11 IEEEELRKHFEDCGDVEAVRIVRDReTGIGKGFGYVLFKDKDSVDL----ALKLNGSKLR-GRKLR 71

RNA recognition motif 1 (RRM1) found in tRNA selenocysteine-associated protein 1 (SECp43); This subgroup corresponds to the RRM1 of SECp43, an RNA-binding protein associated specifically with eukaryotic selenocysteine tRNA [tRNA(Sec)]. It may play an adaptor role in the mechanism of selenocysteine insertion. SECp43 is located primarily in the nucleus and contains two N-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a C-terminal polar/acidic region.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 1934786259   2 MDETEIGSCFGRYG-SVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKIVgsqIHFHGKKLKLGPAIRKQKL 70
Cdd:cd12610    11 MDENFIKRAFATMGeTVLSVKIIRNRvTGGPAGYCFVEFADEATAERCL---HKLNGKPIPGSNPPKRFKL 78

RNA recognition motif 2 (RRM2) found in vertebrate single-stranded DNA-binding protein MSSP-1; This subgroup corresponds to the RRM2 of MSSP-1, also termed RNA-binding motif, single-stranded-interacting protein 1 (RBMS1), or suppressor of CDC2 with RNA-binding motif 2 (SCR2). MSSP-1 is a double- and single-stranded DNA binding protein that belongs to the c-myc single-strand binding proteins (MSSP) family. It specifically recognizes the sequence CT(A/T)(A/T)T, and stimulates DNA replication in the system using SV40 DNA. MSSP-1 is identical with Scr2, a human protein which complements the defect of cdc2 kinase in Schizosaccharomyces pombe. MSSP-1 has been implied in regulating DNA replication, transcription, apoptosis induction, and cell-cycle movement, via the interaction with c-MYC, the product of protooncogene c-myc. MSSP-1 contains two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), both of which are responsible for the specific DNA binding activity as well as induction of apoptosis.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNRTGVSKGYGFVSFVNDVDVQKIVGsqiHFHGKKLKLGPAI 65
Cdd:cd12473    12 MDEQELENMLKPFGQVISTRILRDSSGTSRGVGFARMESTEKCEAVIS---HFNGKFIKTPPGV 72

RNA recognition motif 2 (RRM2) found in heterogeneous nuclear ribonucleoprotein A0 (hnRNP A0) and similar proteins; This subgroup corresponds to the RRM2 of hnRNP A0, a low abundance hnRNP protein that has been implicated in mRNA stability in mammalian cells. It has been identified as the substrate for MAPKAP-K2 and may be involved in the lipopolysaccharide (LPS)-induced post-transcriptional regulation of tumor necrosis factor-alpha (TNF-alpha), cyclooxygenase 2 (COX-2) and macrophage inflammatory protein 2 (MIP-2). hnRNP A0 contains two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), followed by a long glycine-rich region at the C-terminus.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKIVGSQIH-FHGKKLKLGPAIRKQ 68
Cdd:cd12579    11 VGEGDLVEHFSQFGTVEKVEVIADKdTGKKRGFGFVYFEDHDSADKAAVVKFHsINGHRVEVKKAVPKE 79

RNA recognition motif 1 (RRM1) found in vertebrate Hu-antigen B (HuB); This subgroup corresponds to the RRM1 of HuB, also termed ELAV-like protein 2 (ELAV-2), or ELAV-like neuronal protein 1, or nervous system-specific RNA-binding protein Hel-N1 (Hel-N1), one of the neuronal members of the Hu family. The neuronal Hu proteins play important roles in neuronal differentiation, plasticity and memory. HuB is also expressed in gonads and is up-regulated during neuronal differentiation of embryonic carcinoma P19 cells. Like other Hu proteins, HuB contains three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). RRM1 and RRM2 may cooperate in binding to an AU-rich RNA element (ARE). RRM3 may help to maintain the stability of the RNA-protein complex, and might also bind to poly(A) tails or be involved in protein-protein interactions.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|
gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKIVGS 50
Cdd:cd12771    16 MTQEELKSLFGSIGEIESCKLVRDKiTGQSLGYGFVNYIEPKDAEKAINT 65

RNA recognition motif 2 (RRM2) found in heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) and similar proteins; This subgroup corresponds to the RRM2 of hnRNP A2/B1, an RNA trafficking response element-binding protein that interacts with the hnRNP A2 response element (A2RE). Many mRNAs, such as myelin basic protein (MBP), myelin-associated oligodendrocytic basic protein (MOBP), carboxyanhydrase II (CAII), microtubule-associated protein tau, and amyloid precursor protein (APP) are trafficked by hnRNP A2/B1. hnRNP A2/B1 also functions as a splicing factor that regulates alternative splicing of the tumor suppressors, such as BIN1, WWOX, the antiapoptotic proteins c-FLIP and caspase-9B, the insulin receptor (IR), and the RON proto-oncogene among others. Overexpression of hnRNP A2/B1 has been described in many cancers. It functions as a nuclear matrix protein involving in RNA synthesis and the regulation of cellular migration through alternatively splicing pre-mRNA. It may play a role in tumor cell differentiation. hnRNP A2/B1 contains two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), followed by a long glycine-rich region at the C-terminus.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 1934786259   3 DETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKIVGSQIHF-HGKKLKLGPAIRKQ 68
Cdd:cd12581    13 EEHHLRDYFEEYGKIDTIEIITDRqSGKKRGFGFVTFDDHDPVDKIVLQKYHTiNGHNAEVRKALSRQ 80

RNA recognition motif (RRM) found in eukaryotic RNA-binding protein RBM24, RBM38 and similar proteins; This subfamily corresponds to the RRM of RBM24 and RBM38 from vertebrate, SUPpressor family member SUP-12 from Caenorhabditis elegans and similar proteins. Both, RBM24 and RBM38, are preferentially expressed in cardiac and skeletal muscle tissues. They regulate myogenic differentiation by controlling the cell cycle in a p21-dependent or -independent manner. RBM24, also termed RNA-binding region-containing protein 6, interacts with the 3'-untranslated region (UTR) of myogenin mRNA and regulates its stability in C2C12 cells. RBM38, also termed CLL-associated antigen KW-5, or HSRNASEB, or RNA-binding region-containing protein 1(RNPC1), or ssDNA-binding protein SEB4, is a direct target of the p53 family. It is required for maintaining the stability of the basal and stress-induced p21 mRNA by binding to their 3'-UTRs. It also binds the AU-/U-rich elements in p63 3'-UTR and regulates p63 mRNA stability and activity. SUP-12 is a novel tissue-specific splicing factor that controls muscle-specific splicing of the ADF/cofilin pre-mRNA in C. elegans. All family members contain a conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain).

                          10        20        30
                  ....*....|....*....|....*....|....*..
gi 1934786259  11 FGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQK 46
Cdd:cd12384    21 FEQFGEIEEAVVITDRqTGKSRGYGFVTMADREAAER 57

RNA recognition motif (RRM) found in heterogeneous nuclear ribonucleoprotein G (hnRNP G), Y chromosome RNA recognition motif 1 (hRBMY), testis-specific heterogeneous nuclear ribonucleoprotein G-T (hnRNP G-T) and similar proteins; This subfamily corresponds to the RRM domain of hnRNP G, also termed glycoprotein p43 or RBMX, an RNA-binding motif protein located on the X chromosome. It is expressed ubiquitously and has been implicated in the splicing control of several pre-mRNAs. Moreover, hnRNP G may function as a regulator of transcription for SREBP-1c and GnRH1. Research has shown that hnRNP G may also act as a tumor-suppressor since it upregulates the Txnip gene and promotes the fidelity of DNA end-joining activity. In addition, hnRNP G appears to play a critical role in proper neural development of zebrafish and frog embryos. The family also includes several paralogs of hnRNP G, such as hRBMY and hnRNP G-T (also termed RNA-binding motif protein, X-linked-like-2). Both, hRBMY and hnRNP G-T, are exclusively expressed in testis and critical for male fertility. Like hnRNP G, hRBMY and hnRNP G-T interact with factors implicated in the regulation of pre-mRNA splicing, such as hTra2-beta1 and T-STAR. Although members in this family share a high conserved N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), they appear to recognize different RNA targets. For instance, hRBMY interacts specifically with a stem-loop structure in which the loop is formed by the sequence CA/UCAA. In contrast, hnRNP G associates with single stranded RNA sequences containing a CCA/C motif. In addition to the RRM, hnRNP G contains a nascent transcripts targeting domain (NTD) in the middle region and a novel auxiliary RNA-binding domain (RBD) in its C-terminal region. The C-terminal RBD exhibits distinct RNA binding specificity, and would play a critical role in the regulation of alternative splicing by hnRNP G.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 1934786259   3 DETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVD----VQKIVGSQIhfHGKKLKLGPAIR 66
Cdd:cd12382    14 NEKALEAVFGKYGRIVEVLLMKDReTNKSRGFAFVTFESPADakdaARDMNGKEL--DGKAIKVEQATK 80

RNA recognition motif 1 (RRM1) found in vertebrate Hu-antigen D (HuD); This subgroup corresponds to the RRM1 of HuD, also termed ELAV-like protein 4 (ELAV-4), or paraneoplastic encephalomyelitis antigen HuD, one of the neuronal members of the Hu family. The neuronal Hu proteins play important roles in neuronal differentiation, plasticity and memory. HuD has been implicated in various aspects of neuronal function, such as the commitment and differentiation of neuronal precursors as well as synaptic remodeling in mature neurons. HuD also functions as an important regulator of mRNA expression in neurons by interacting with AU-rich RNA element (ARE) and stabilizing multiple transcripts. Moreover, HuD regulates the nuclear processing/stability of N-myc pre-mRNA in neuroblastoma cells, as well as the neurite elongation and morphological differentiation. HuD specifically binds poly(A) RNA. Like other Hu proteins, HuD contains three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). RRM1 and RRM2 may cooperate in binding to an ARE. RRM3 may help to maintain the stability of the RNA-protein complex, and might also bind to poly(A) tails or be involved in protein-protein interactions.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|
gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKIVGS 50
Cdd:cd12770    13 MTQEEFRSLFGSIGEIESCKLVRDKiTGQSLGYGFVNYIDPKDAEKAINT 62

RNA recognition motif 3 (RRM3) found in RNA-binding protein 19 (RBM19) and RNA recognition motif 2 found in multiple RNA-binding domain-containing protein 1 (MRD1); This subfamily corresponds to the RRM3 of RBM19 and RRM2 of MRD1. RBM19, also termed RNA-binding domain-1 (RBD-1), is a nucleolar protein conserved in eukaryotes involved in ribosome biogenesis by processing rRNA and is essential for preimplantation development. It has a unique domain organization containing 6 conserved RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). MRD1 is encoded by a novel yeast gene MRD1 (multiple RNA-binding domain). It is well conserved in yeast and its homologs exist in all eukaryotes. MRD1 is present in the nucleolus and the nucleoplasm. It interacts with the 35 S precursor rRNA (pre-rRNA) and U3 small nucleolar RNAs (snoRNAs). It is essential for the initial processing at the A0-A2 cleavage sites in the 35 S pre-rRNA. MRD1 contains 5 conserved RRMs, which may play an important structural role in organizing specific rRNA processing events.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....
gi 1934786259   4 ETEIGSCFGRYGSVKEVKI-ITNRTGVSKGYGFVSFVNDVDVQK 46
Cdd:cd12316    13 EDELRELFEAFGKISEVHIpLDKQTKRSKGFAFVLFVIPEDAVK 56

RNA recognition motif (RRM) found in eukaryotic translation initiation factor 3 subunit G (eIF-3G) and similar proteins; This subfamily corresponds to the RRM of eIF-3G and similar proteins. eIF-3G, also termed eIF-3 subunit 4, or eIF-3-delta, or eIF3-p42, or eIF3-p44, is the RNA-binding subunit of eIF3, a large multisubunit complex that plays a central role in the initiation of translation by binding to the 40 S ribosomal subunit and promoting the binding of methionyl-tRNAi and mRNA. eIF-3G binds 18 S rRNA and beta-globin mRNA, and therefore appears to be a nonspecific RNA-binding protein. eIF-3G is one of the cytosolic targets and interacts with mature apoptosis-inducing factor (AIF). eIF-3G contains one RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). This family also includes yeast eIF3-p33, a homolog of vertebrate eIF-3G, plays an important role in the initiation phase of protein synthesis in yeast. It binds both, mRNA and rRNA, fragments due to an RRM near its C-terminus.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQK 46
Cdd:cd12408    11 ATEEDLRELFRPFGPISRVYLAKDKeTGQSKGFAFVTFETREDAER 56

RNA recognition motif 1 (RRM1) and 2 (RRM2) found in CELF/Bruno-like family of RNA binding proteins and plant flowering time control protein FCA; This subfamily corresponds to the RRM1 and RRM2 domains of the CUGBP1 and ETR-3-like factors (CELF) as well as plant flowering time control protein FCA. CELF, also termed BRUNOL (Bruno-like) proteins, is a family of structurally related RNA-binding proteins involved in regulation of pre-mRNA splicing in the nucleus, and control of mRNA translation and deadenylation in the cytoplasm. The family contains six members: CELF-1 (also known as BRUNOL-2, CUG-BP1, NAPOR, EDEN-BP), CELF-2 (also known as BRUNOL-3, ETR-3, CUG-BP2, NAPOR-2), CELF-3 (also known as BRUNOL-1, TNRC4, ETR-1, CAGH4, ER DA4), CELF-4 (BRUNOL-4), CELF-5 (BRUNOL-5) and CELF-6 (BRUNOL-6). They all contain three highly conserved RNA recognition motifs (RRMs), also known as RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains): two consecutive RRMs (RRM1 and RRM2) situated in the N-terminal region followed by a linker region and the third RRM (RRM3) close to the C-terminus of the protein. The low sequence conservation of the linker region is highly suggestive of a large variety in the co-factors that associate with the various CELF family members. Based on both, sequence similarity and function, the CELF family can be divided into two subfamilies, the first containing CELFs 1 and 2, and the second containing CELFs 3, 4, 5, and 6. The different CELF proteins may act through different sites on at least some substrates. Furthermore, CELF proteins may interact with each other in varying combinations to influence alternative splicing in different contexts. This subfamily also includes plant flowering time control protein FCA that functions in the posttranscriptional regulation of transcripts involved in the flowering process. FCA contains two RRMs, and a WW protein interaction domain.

                          10        20        30
                  ....*....|....*....|....*....|....*...
gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSF 38
Cdd:cd12361    11 ASEEDVRPLFEQFGNIEEVQILRDKqTGQSKGCAFVTF 48

RNA recognition motif 5 (RRM5) found in RNA-binding protein 19 (RBM19 or RBD-1) and similar proteins; This subfamily corresponds to the RRM5 of RBM19 and RRM4 of MRD1. RBM19, also termed RNA-binding domain-1 (RBD-1), is a nucleolar protein conserved in eukaryotes involved in ribosome biogenesis by processing rRNA and is essential for preimplantation development. It has a unique domain organization containing 6 conserved RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 1934786259  11 FGRYGSVKEVKIITNRT----GVSKGYGFVSFVNDVDVQKIV----GSQIHFHGKKLKL 61
Cdd:cd12318    21 FEKCGPIRSVTIAKKKDpkgpLLSMGYGFVEFKSPEAAQKALkqlqGTVLDGHALELKI 79

RNA recognition motif (RRM) found in ras GTPase-activating protein-binding protein G3BP1, G3BP2 and similar proteins; This subfamily corresponds to the RRM domain in the G3BP family of RNA-binding and SH3 domain-binding proteins. G3BP acts at the level of RNA metabolism in response to cell signaling, possibly as RNA transcript stabilizing factors or an RNase. Members include G3BP1, G3BP2 and similar proteins. These proteins associate directly with the SH3 domain of GTPase-activating protein (GAP), which functions as an inhibitor of Ras. They all contain an N-terminal nuclear transfer factor 2 (NTF2)-like domain, an acidic domain, a domain containing PXXP motif(s), an RNA recognition motif (RRM), and an Arg-Gly-rich region (RGG-rich region, or arginine methylation motif).

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*..
gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNRTGVS-KGYGFVSFVNDVDVQKI 47
Cdd:cd12229    15 ITEDELKEFFSRFGNVLELRINSKGGGGRlPNFGFVVFDDPEAVQKI 61

RNA recognition motif 2 (RRM2) found in nucleolin-like proteins mainly from plants; This subfamily corresponds to the RRM2 of a group of plant nucleolin-like proteins, including nucleolin 1 (also termed protein nucleolin like 1) and nucleolin 2 (also termed protein nucleolin like 2, or protein parallel like 1). They play roles in the regulation of ribosome synthesis and in the growth and development of plants. Like yeast nucleolin, nucleolin-like proteins possess two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                          10        20        30
                  ....*....|....*....|....*....|....*.
gi 1934786259   4 ETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSF 38
Cdd:cd12451    17 RDELREHFGECGEVTNVRIPTDReTGELKGFAYIEF 52

RNA recognition motif 2 (RRM2) found in heterogeneous nuclear ribonucleoprotein A3 (hnRNP A3) and similar proteins; This subgroup corresponds to the RRM2 of hnRNP A3, a novel RNA trafficking response element-binding protein that interacts with the hnRNP A2 response element (A2RE) independently of hnRNP A2 and participates in the trafficking of A2RE-containing RNA. hnRNP A3 can shuttle between the nucleus and the cytoplasm. It contains two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), followed by a long glycine-rich region at the C-terminus.

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gi 1934786259   3 DETEIGSCFGRYGSVKEVKIITNR-TGVSKGYGFVSFVNDVDVQKIVGSQIH-FHGKKLKLGPAIRKQ 68
Cdd:cd12582    13 EEYHLRDYFEKYGKIETIEVMEDRqSGKKRGFAFVTFDDHDTVDKIVVQKYHtINGHNCEVKKALSKQ 80

RNA recognition motif 2 (RRM2) found in CUGBP Elav-like family member CELF-3, CELF-4, CELF-5, CELF-6 and similar proteins; This subgroup corresponds to the RRM2 of CELF-3, CELF-4, CELF-5, and CELF-6, all of which belong to the CUGBP1 and ETR-3-like factors (CELF) or BRUNOL (Bruno-like) family of RNA-binding proteins that display dual nuclear and cytoplasmic localizations and have been implicated in the regulation of pre-mRNA splicing and in the control of mRNA translation and deadenylation. CELF-3, expressed in brain and testis only, is also known as bruno-like protein 1 (BRUNOL-1), or CAG repeat protein 4, or CUG-BP- and ETR-3-like factor 3, or embryonic lethal abnormal vision (ELAV)-type RNA-binding protein 1 (ETR-1), or expanded repeat domain protein CAG/CTG 4, or trinucleotide repeat-containing gene 4 protein (TNRC4). It plays an important role in the pathogenesis of tauopathies. CELF-3 contains three highly conserved RNA recognition motifs (RRMs), also known as RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains): two consecutive RRMs (RRM1 and RRM2) situated in the N-terminal region followed by a linker region and the third RRM (RRM3) close to the C-terminus of the protein. The effect of CELF-3 on tau splicing is mediated mainly by the RNA-binding activity of RRM2. The divergent linker region might mediate the interaction of CELF-3 with other proteins regulating its activity or involved in target recognition. CELF-4, being highly expressed throughout the brain and in glandular tissues, moderately expressed in heart, skeletal muscle, and liver, is also known as bruno-like protein 4 (BRUNOL-4), or CUG-BP- and ETR-3-like factor 4. Like CELF-3, CELF-4 also contain three highly conserved RRMs. The splicing activation or repression activity of CELF-4 on some specific substrates is mediated by its RRM1/RRM2. On the other hand, both RRM1 and RRM2 of CELF-4 can activate cardiac troponin T (cTNT) exon 5 inclusion. CELF-5, expressed in brain, is also known as bruno-like protein 5 (BRUNOL-5), or CUG-BP- and ETR-3-like factor 5. Although its biological role remains unclear, CELF-5 shares same domain architecture with CELF-3. CELF-6, being strongly expressed in kidney, brain, and testis, is also known as bruno-like protein 6 (BRUNOL-6), or CUG-BP- and ETR-3-like factor 6. It activates exon inclusion of a cardiac troponin T minigene in transient transfection assays in a muscle-specific splicing enhancer (MSE)-dependent manner and can activate inclusion via multiple copies of a single element, MSE2. CELF-6 also promotes skipping of exon 11 of insulin receptor, a known target of CELF activity that is expressed in kidney. In addition to three highly conserved RRMs, CELF-6 also possesses numerous potential phosphorylation sites, a potential nuclear localization signal (NLS) at the C terminus, and an alanine-rich region within the divergent linker region.

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gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNRTGVSKGYGFVSFVNDVDVQKIV----GSQI 52
Cdd:cd12635    13 QSEDDVRRLFEPFGSIEECTILRGPDGNSKGCAFVKFSSHAEAQAAInalhGSQT 67

RNA recognition motif 2 (RRM2) found in the c-myc gene single-strand binding proteins (MSSP) family; This subfamily corresponds to the RRM2 of c-myc gene single-strand binding proteins (MSSP) family, including single-stranded DNA-binding protein MSSP-1 (also termed RBMS1 or SCR2) and MSSP-2 (also termed RBMS2 or SCR3). All MSSP family members contain two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), both of which are responsible for the specific DNA binding activity. Both, MSSP-1 and -2, have been identified as protein factors binding to a putative DNA replication origin/transcriptional enhancer sequence present upstream from the human c-myc gene in both single- and double-stranded forms. Thus they have been implied in regulating DNA replication, transcription, apoptosis induction, and cell-cycle movement, via the interaction with C-MYC, the product of protooncogene c-myc. Moreover, they family includes a new member termed RNA-binding motif, single-stranded-interacting protein 3 (RBMS3), which is not a transcriptional regulator. RBMS3 binds with high affinity to A/U-rich stretches of RNA, and to A/T-rich DNA sequences, and functions as a regulator of cytoplasmic activity. In addition, a putative meiosis-specific RNA-binding protein termed sporulation-specific protein 5 (SPO5, or meiotic RNA-binding protein 1, or meiotically up-regulated gene 12 protein), encoded by Schizosaccharomyces pombe Spo5/Mug12 gene, is also included in this family. SPO5 is a novel meiosis I regulator that may function in the vicinity of the Mei2 dot.

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gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIITNRTGVSKGYGFVSFVNDVDVQKIVGsqiHFHGKKLKlGPAIRKQKLCAR 73
Cdd:cd12244    12 MDEQDLENMLKPFGQVISTRILRDSKGQSRGVGFARMESREKCEDVIS---KFNGKVLK-TPSASGEPLLVK 79

RNA recognition motif (RRM) found in ras GTPase-activating protein-binding protein 1 (G3BP1) and similar proteins; This subgroup corresponds to the RRM of G3BP1, also termed ATP-dependent DNA helicase VIII (DH VIII), or GAP SH3 domain-binding protein 1, which has been identified as a phosphorylation-dependent endoribonuclease that interacts with the SH3 domain of RasGAP, a multi-functional protein controlling Ras activity. The acidic RasGAP binding domain of G3BP1 harbors an arsenite-regulated phosphorylation site and dominantly inhibits stress granule (SG) formation. G3BP1 also contains an N-terminal nuclear transfer factor 2 (NTF2)-like domain, an RNA recognition motif (RRM domain), and an Arg-Gly-rich region (RGG-rich region, or arginine methylation motif). The RRM domain and RGG-rich region are canonically associated with RNA binding. G3BP1 co-immunoprecipitates with mRNAs. It binds to and cleaves the 3'-untranslated region (3'-UTR) of the c-myc mRNA in a phosphorylation-dependent manner. Thus, G3BP1 may play a role in coupling extra-cellular stimuli to mRNA stability. It has been shown that G3BP1 is a novel Dishevelled-associated protein that is methylated upon Wnt3a stimulation and that arginine methylation of G3BP1 regulates both Ctnnb1 mRNA and canonical Wnt/beta-catenin signaling. Furthermore, G3BP1 can be associated with the 3'-UTR of beta-F1 mRNA in cytoplasmic RNA-granules, demonstrating that G3BP1 may specifically repress the translation of the transcript.

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gi 1934786259   2 MDETEIGSCFGRYGSVKEVKIitNRTGVSKGYGFVSFVNDVDVQKIVGSQ-IHFHG 56
Cdd:cd12463    15 VDKSELKEFFQGYGNVVELRI--NSGGKLPNFGFVVFDDPEPVQKILSNRpIKFRG 68