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        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 530371379  825 GYLIHVGGLCPSVSEADLRSHFQKYQVSEISIYD-STNYRYASLAFTKNSDAKIAVKEMNGIEINGKSVNVWPVKIL 900
Cdd:cd12248     1 CVYVHVGNLAPSVSEEDLLMHFEKYHVSKISIQKlSMNYRYASLTFDDASDAQAAVKEMNGKDISGRKVKVRYVKES 77

RNA recognition motif (RRM) found in RNA-binding protein 44 (RBM44) and similar proteins; This subgroup corresponds to the RRM of RBM44, a novel germ cell intercellular bridge protein that is localized in the cytoplasm and intercellular bridges from pachytene to secondary spermatocyte stages. RBM44 interacts with itself and testis-expressed gene 14 (TEX14). Unlike TEX14, RBM44 does not function in the formation of stable intercellular bridges. It carries an RNA recognition motif (RRM) that could potentially bind a multitude of RNA sequences in the cytoplasm and help to shuttle them through the intercellular bridge, facilitating their dispersion into the interconnected neighboring cells.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 530371379  825 GYLIHVGGLCPSVSEADLRSHFQKYQVSEISIYD-STNYRYASLAFTKNSDAKIAVKEMNGIEINGKSVNVWPVKIL 900
Cdd:cd12248     1 CVYVHVGNLAPSVSEEDLLMHFEKYHVSKISIQKlSMNYRYASLTFDDASDAQAAVKEMNGKDISGRKVKVRYVKES 77

RNA recognition motif. (a.k.a. RRM, RBD, or RNP domain); The RRM motif is probably diagnostic of an RNA binding protein. RRMs are found in a variety of RNA binding proteins, including various hnRNP proteins, proteins implicated in regulation of alternative splicing, and protein components of snRNPs. The motif also appears in a few single stranded DNA binding proteins. The RRM structure consists of four strands and two helices arranged in an alpha/beta sandwich, with a third helix present during RNA binding in some cases The C-terminal beta strand (4th strand) and final helix are hard to align and have been omitted in the SEED alignment The LA proteins have an N terminal rrm which is included in the seed. There is a second region towards the C terminus that has some features characteriztic of a rrm but does not appear to have the important structural core of a rrm. The LA proteins are one of the main autoantigens in Systemic lupus erythematosus (SLE), an autoimmune disease.

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 530371379   828 IHVGGLCPSVSEADLRSHFQKY-QVSEISI-YDST--NYRYASLAFTKNSDAKIAVKEMNGIEINGKSV 892
Cdd:pfam00076    1 LFVGNLPPDTTEEDLKDLFSKFgPIKSIRLvRDETgrSKGFAFVEFEDEEDAEKAIEALNGKELGGREL 69

RNA recognition motif (RRM) found in RNA-binding protein 44 (RBM44) and similar proteins; This subgroup corresponds to the RRM of RBM44, a novel germ cell intercellular bridge protein that is localized in the cytoplasm and intercellular bridges from pachytene to secondary spermatocyte stages. RBM44 interacts with itself and testis-expressed gene 14 (TEX14). Unlike TEX14, RBM44 does not function in the formation of stable intercellular bridges. It carries an RNA recognition motif (RRM) that could potentially bind a multitude of RNA sequences in the cytoplasm and help to shuttle them through the intercellular bridge, facilitating their dispersion into the interconnected neighboring cells.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 530371379  825 GYLIHVGGLCPSVSEADLRSHFQKYQVSEISIYD-STNYRYASLAFTKNSDAKIAVKEMNGIEINGKSVNVWPVKIL 900
Cdd:cd12248     1 CVYVHVGNLAPSVSEEDLLMHFEKYHVSKISIQKlSMNYRYASLTFDDASDAQAAVKEMNGKDISGRKVKVRYVKES 77

RNA recognition motif;

                            10        20        30        40        50        60        70
                    ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 530371379    828 IHVGGLCPSVSEADLRSHFQKY-QVSEISI-YDSTNYR---YASLAFTKNSDAKIAVKEMNGIEINGKSVNV 894
Cdd:smart00360    2 LFVGNLPPDTTEEELRELFSKFgKVESVRLvRDKETGKskgFAFVEFESEEDAEKALEALNGKELDGRPLKV 73

RNA recognition motif. (a.k.a. RRM, RBD, or RNP domain); The RRM motif is probably diagnostic of an RNA binding protein. RRMs are found in a variety of RNA binding proteins, including various hnRNP proteins, proteins implicated in regulation of alternative splicing, and protein components of snRNPs. The motif also appears in a few single stranded DNA binding proteins. The RRM structure consists of four strands and two helices arranged in an alpha/beta sandwich, with a third helix present during RNA binding in some cases The C-terminal beta strand (4th strand) and final helix are hard to align and have been omitted in the SEED alignment The LA proteins have an N terminal rrm which is included in the seed. There is a second region towards the C terminus that has some features characteriztic of a rrm but does not appear to have the important structural core of a rrm. The LA proteins are one of the main autoantigens in Systemic lupus erythematosus (SLE), an autoimmune disease.

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 530371379   828 IHVGGLCPSVSEADLRSHFQKY-QVSEISI-YDST--NYRYASLAFTKNSDAKIAVKEMNGIEINGKSV 892
Cdd:pfam00076    1 LFVGNLPPDTTEEDLKDLFSKFgPIKSIRLvRDETgrSKGFAFVEFEDEEDAEKAIEALNGKELGGREL 69

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        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 530371379  828 IHVGGLCPSVSEADLRSHFQKY-QVSEIS-IYDSTNYR---YASLAFTKNSDAKIAVKEMNGIEINGKSVNV 894
Cdd:cd12382     4 LFIGGLNTETNEKALEAVFGKYgRIVEVLlMKDRETNKsrgFAFVTFESPADAKDAARDMNGKELDGKAIKV 75

RNA recognition motif 2 (RRM2) found in Deleted in azoospermia-associated protein 1 (DAZAP1) and similar proteins; This subfamily corresponds to the RRM2 of DAZAP1 or DAZ-associated protein 1, also termed proline-rich RNA binding protein (Prrp), a multi-functional ubiquitous RNA-binding protein expressed most abundantly in the testis and essential for normal cell growth, development, and spermatogenesis. DAZAP1 is a shuttling protein whose acetylated is predominantly nuclear and the nonacetylated form is in cytoplasm. DAZAP1 also functions as a translational regulator that activates translation in an mRNA-specific manner. DAZAP1 was initially identified as a binding partner of Deleted in Azoospermia (DAZ). It also interacts with numerous hnRNPs, including hnRNP U, hnRNP U like-1, hnRNPA1, hnRNPA/B, and hnRNP D, suggesting DAZAP1 might associate and cooperate with hnRNP particles to regulate adenylate-uridylate-rich elements (AU-rich element or ARE)-containing mRNAs. DAZAP1 contains two N-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a C-terminal proline-rich domain.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 530371379  824 KGYLIHVGGLCPSVSEADLRSHFQKY-QVSEIS-IYDSTNYR---YASLAFTKNSDAKIAVKeMNGIEINGKSVNV 894
Cdd:cd12327     1 KSKKVFVGGIPHNCGETELRDYFKRYgVVTEVVmMYDAEKQRsrgFGFITFEDEQSVDQAVN-MHFHDIMGKKVEV 75

RNA recognition motif 2 (RRM2) found in granule-associated RNA binding proteins (p40-TIA-1 and TIAR), and yeast nuclear and cytoplasmic polyadenylated RNA-binding protein PUB1; This subfamily corresponds to the RRM3 of TIA-1, TIAR, and PUB1. Nucleolysin TIA-1 isoform p40 (p40-TIA-1 or TIA-1) and nucleolysin TIA-1-related protein (TIAR) are granule-associated RNA binding proteins involved in inducing apoptosis in cytotoxic lymphocyte (CTL) target cells. They share high sequence similarity and are expressed in a wide variety of cell types. TIA-1 can be phosphorylated by a serine/threonine kinase that is activated during Fas-mediated apoptosis.TIAR is mainly localized in the nucleus of hematopoietic and nonhematopoietic cells. It is translocated from the nucleus to the cytoplasm in response to exogenous triggers of apoptosis. Both TIA-1 and TIAR bind specifically to poly(A) but not to poly(C) homopolymers. They are composed of three N-terminal highly homologous RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a glutamine-rich C-terminal auxiliary domain containing a lysosome-targeting motif. TIA-1 and TIAR interact with RNAs containing short stretches of uridylates and their RRM2 can mediate the specific binding to uridylate-rich RNAs. The C-terminal auxiliary domain may be responsible for interacting with other proteins. In addition, TIA-1 and TIAR share a potential serine protease-cleavage site (Phe-Val-Arg) localized at the junction between their RNA binding domains and their C-terminal auxiliary domains. This subfamily also includes a yeast nuclear and cytoplasmic polyadenylated RNA-binding protein PUB1, termed ARS consensus-binding protein ACBP-60, or poly uridylate-binding protein, or poly(U)-binding protein, which has been identified as both a heterogeneous nuclear RNA-binding protein (hnRNP) and a cytoplasmic mRNA-binding protein (mRNP). It may be stably bound to a translationally inactive subpopulation of mRNAs within the cytoplasm. PUB1 is distributed in both, the nucleus and the cytoplasm, and binds to poly(A)+ RNA (mRNA or pre-mRNA). Although it is one of the major cellular proteins cross-linked by UV light to polyadenylated RNAs in vivo, PUB1 is nonessential for cell growth in yeast. PUB1 also binds to T-rich single stranded DNA (ssDNA); however, there is no strong evidence implicating PUB1 in the mechanism of DNA replication. PUB1 contains three RRMs, and a GAR motif (glycine and arginine rich stretch) that is located between RRM2 and RRM3.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 530371379  828 IHVGGLCPSVSEADLRSHFQKY-QVSEISIYDSTNyrYASLAFTKNSDAKIAVKEMNGIEINGKSV 892
Cdd:cd12354     3 VYVGNITKGLTEALLQQTFSPFgQILEVRVFPDKG--YAFIRFDSHEAATHAIVSVNGTIINGQAV 66

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 530371379   828 IHVGGLCPSVSEADLRSHFQKY-QVSEISI-YDSTNYR---YASLAFTKNSDAKIAVKEMNGIEINGKsvnvwPVKILGE 902
Cdd:TIGR01628    3 LYVGDLDPDVTEAKLYDLFKPFgPVLSVRVcRDSVTRRslgYGYVNFQNPADAERALETMNFKRLGGK-----PIRIMWS 77

                           90       100       110
                   ....*....|....*....|....*....|...
gi 530371379   903 YTSPLSSKNGN-RISSNNLEKS-TNKQIHSEFS 933
Cdd:TIGR01628   78 QRDPSLRRSGVgNIFVKNLDKSvDNKALFDTFS 110

RNA recognition motif (RRM) found in transformer-2 protein homolog TRA2-alpha, TRA2-beta and similar proteins; This subfamily corresponds to the RRM of two mammalian homologs of Drosophila transformer-2 (Tra2), TRA2-alpha, TRA2-beta (also termed SFRS10), and similar proteins found in eukaryotes. TRA2-alpha is a 40-kDa serine/arginine-rich (SR) protein that specifically binds to gonadotropin-releasing hormone (GnRH) exonic splicing enhancer on exon 4 (ESE4) and is necessary for enhanced GnRH pre-mRNA splicing. It strongly stimulates GnRH intron A excision in a dose-dependent manner. In addition, TRA2-alpha can interact with either 9G8 or SRp30c, which may also be crucial for ESE-dependent GnRH pre-mRNA splicing. TRA2-beta is a serine/arginine-rich (SR) protein that controls the pre-mRNA alternative splicing of the calcitonin/calcitonin gene-related peptide (CGRP), the survival motor neuron 1 (SMN1) protein and the tau protein. Both, TRA2-alpha and TRA2-beta, contains a well conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), flanked by the N- and C-terminal arginine/serine (RS)-rich regions.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 530371379  830 VGGLCPSVSEADLRSHFQKY-QVSEISI-YDSTNYR---YASLAFTKNSDAKIAVKEMNGIEINGKSVNV 894
Cdd:cd12363     6 VFGLSLYTTERDLREVFSRYgPIEKVQVvYDQQTGRsrgFGFVYFESVEDAKEAKERLNGQEIDGRRIRV 75

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        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 530371379  830 VGGLCPSVSEADLRSHFQKY-QVSEIS-IYDSTNYR---YASLAFTKNSDAKIAVKEMNGIEINGKSVNV 894
Cdd:cd12449     5 VGGLSFDTNEQSLEEVFSKYgQISEVVvVKDRETQRsrgFGFVTFENPDDAKDAMMAMNGKSLDGRQIRV 74

RNA recognition motif (RRM) found in the Aly/REF family; This subfamily corresponds to the RRM of Aly/REF family which includes THO complex subunit 4 (THOC4, also termed Aly/REF), S6K1 Aly/REF-like target (SKAR, also termed PDIP3 or PDIP46) and similar proteins. THOC4 is an mRNA transporter protein with a well conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). It is involved in RNA transportation from the nucleus, and was initially identified as a transcription coactivator of LEF-1 and AML-1 for the TCRalpha enhancer function. In addition, THOC4 specifically binds to rhesus (RH) promoter in erythroid, and might be a novel transcription cofactor for erythroid-specific genes. SKAR shows high sequence homology with THOC4 and possesses one RRM as well. SKAR is widely expressed and localizes to the nucleus. It may be a critical player in the function of S6K1 in cell and organism growth control by binding the activated, hyperphosphorylated form of S6K1 but not S6K2. Furthermore, SKAR functions as a protein partner of the p50 subunit of DNA polymerase delta. In addition, SKAR may have particular importance in pancreatic beta cell size determination and insulin secretion.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 530371379  828 IHVGGLCPSVSEADLRSHFQK-YQVSEISI-YDSTNYRY--ASLAFTKNSDAKIAVKEMNGIEINGK 890
Cdd:cd12418     3 VRVSNLHPDVTEEDLRELFGRvGPVKSVKInYDRSGRSTgtAYVVFERPEDAEKAIKQFDGVLLDGQ 69

RNA recognition motif 3 (RRM3) found in yeast negative growth regulatory protein NGR1 (RBP1), yeast protein NAM8 and similar proteins; This subfamily corresponds to the RRM3 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        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 530371379  828 IHVGGLCPSVSEADLRSHFQKY-QVSEISIYDSTNYRYasLAFTKNSDAKIAVKEMNGIEINGKSV 892
Cdd:cd12346     4 VFVGGLDPNVTEEDLRVLFGPFgEIVYVKIPPGKGCGF--VQFVNRASAEAAIQKLQGTPIGGSRI 67

RNA recognition motif (RRM) found in AZoospermia (DAZ) autosomal homologs, DAZL (DAZ-like) and BOULE; This subfamily corresponds to the RRM domain of two Deleted in AZoospermia (DAZ) autosomal homologs, DAZL (DAZ-like) and BOULE. BOULE is the founder member of the family and DAZL arose from BOULE in an ancestor of vertebrates. The DAZ gene subsequently originated from a duplication transposition of the DAZL gene. Invertebrates contain a single DAZ homolog, BOULE, while vertebrates, other than catarrhine primates, possess both BOULE and DAZL genes. The catarrhine primates possess BOULE, DAZL, and DAZ genes. The family members encode closely related RNA-binding proteins that are required for fertility in numerous organisms. These proteins contain an RNA recognition motif (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a varying number of copies of a DAZ motif, believed to mediate protein-protein interactions. DAZL and BOULE contain a single copy of the DAZ motif, while DAZ proteins can contain 8-24 copies of this repeat. 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        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 530371379  828 IHVGGLCPSVSEADLRSHFQKY-QVSEISI---YDSTNYRYASLAFTKNSDAKIAVKEMNGIEINGKSVNVWPV 897
Cdd:cd12412     5 IFVGGIDWDTTEEELREFFSKFgKVKDVKIikdRAGVSKGYGFVTFETQEDAEKIQKWGANLVFKGKKLNVGPA 78

RNA recognition motif 1 (RRM1) found in the p54nrb/PSF/PSP1 family; This subfamily corresponds to the RRM1 of the p54nrb/PSF/PSP1 family, including 54 kDa nuclear RNA- and DNA-binding protein (p54nrb or NonO or NMT55), polypyrimidine tract-binding protein (PTB)-associated-splicing factor (PSF or POMp100), paraspeckle protein 1 (PSP1 or PSPC1), which are ubiquitously expressed and are conserved in vertebrates. p54nrb is a multi-functional protein involved in numerous nuclear processes including transcriptional regulation, splicing, DNA unwinding, nuclear retention of hyperedited double-stranded RNA, viral RNA processing, control of cell proliferation, and circadian rhythm maintenance. PSF is also a multi-functional protein that binds RNA, single-stranded DNA (ssDNA), double-stranded DNA (dsDNA) and many factors, and mediates diverse activities in the cell. PSP1 is a novel nucleolar factor that accumulates within a new nucleoplasmic compartment, termed paraspeckles, and diffusely distributes in the nucleoplasm. The cellular function of PSP1 remains unknown currently. This subfamily also includes some p54nrb/PSF/PSP1 homologs from invertebrate species, such as the Drosophila melanogaster gene no-ontransient A (nonA) encoding puff-specific protein Bj6 (also termed NONA) and Chironomus tentans hrp65 gene encoding protein Hrp65. D. melanogaster NONA is involved in eye development and behavior, and may play a role in circadian rhythm maintenance, similar to vertebrate p54nrb. C. tentans Hrp65 is a component of nuclear fibers associated with ribonucleoprotein particles in transit from the gene to the nuclear pore. All family members contain a DBHS domain (for Drosophila behavior, human splicing), which comprises two conserved RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a charged protein-protein interaction module. PSF has an additional large N-terminal domain that differentiates it from other family members.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 530371379  830 VGGLCPSVSEADLRSHFQKY-QVSEISIYDSTNYRYASLAFTKNsdAKIAVKEMNGIEINGKSVNV 894
Cdd:cd12332     6 VGNLPNDITEEEFKELFQKYgEVSEVFLNKGKGFGFIRLDTRAN--AEAAKAELDGTPRKGRQLRV 69

RNA recognition motif (RRM) found in Transformer-2 protein homolog beta (TRA-2 beta) and similar proteins; This subgroup corresponds to the RRM of TRA2-beta or TRA-2-beta, also termed splicing factor, arginine/serine-rich 10 (SFRS10), or transformer-2 protein homolog B, a mammalian homolog of Drosophila transformer-2 (Tra2). TRA2-beta is a serine/arginine-rich (SR) protein that controls the pre-mRNA alternative splicing of the calcitonin/calcitonin gene-related peptide (CGRP), the survival motor neuron 1 (SMN1) protein and the tau protein. It contains a well conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), flanked by the N- and C-terminal arginine/serine (RS)-rich regions. TRA2-beta specifically binds to two types of RNA sequences, the CAA and (GAA)2 sequences, through the RRMs in different RNA binding modes.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 530371379  830 VGGLCPSVSEADLRSHFQKY-QVSEISI-YDSTNYR---YASLAFTKNSDAKIAVKEMNGIEINGKSVNV 894
Cdd:cd12641    12 VFGLSLYTTERDLREVFSKYgPIADVSIvYDQQSRRsrgFAFVYFENVDDAKEAKERANGMELDGRRIRV 81

RNA recognition motif 2 (RRM2) found in yeast nuclear and cytoplasmic polyadenylated RNA-binding protein PUB1 and similar proteins; This subgroup corresponds to the RRM2 of yeast protein PUB1, also termed ARS consensus-binding protein ACBP-60, or poly uridylate-binding protein, or poly(U)-binding protein. PUB1 has been identified as both, a heterogeneous nuclear RNA-binding protein (hnRNP) and a cytoplasmic mRNA-binding protein (mRNP), which may be stably bound to a translationally inactive subpopulation of mRNAs within the cytoplasm. It is distributed in both, the nucleus and the cytoplasm, and binds to poly(A)+ RNA (mRNA or pre-mRNA). Although it is one of the major cellular proteins cross-linked by UV light to polyadenylated RNAs in vivo, PUB1 is nonessential for cell growth in yeast. PUB1 also binds to T-rich single stranded DNA (ssDNA). However, there is no strong evidence implicating PUB1 in the mechanism of DNA replication. PUB1 contains three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a GAR motif (glycine and arginine rich stretch) that is located between RRM2 and RRM3.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 530371379  825 GYLIHVGGLCPSVSEADLRSHFQKY-QVSEISI-YDSTNYR---YASLAFTKNSDAKIAVKEMNGIEINGKSVNV-WPVK 898
Cdd:cd12619     1 HFNIFVGDLSPEVTDAALFNAFSDFpSCSDARVmWDQKTGRsrgYGFVSFRSQQDAQNAINSMNGKWLGSRPIRCnWATK 80

RNA recognition motif 2 (RRM2) found in the Spen (split end) protein family; This subfamily corresponds to the RRM2 domain in the Spen (split end) protein family which includes RNA binding motif protein 15 (RBM15), putative RNA binding motif protein 15B (RBM15B), and similar proteins found in Metazoa. RBM15, also termed one-twenty two protein 1 (OTT1), conserved in eukaryotes, is a novel mRNA export factor and component of the NXF1 pathway. It binds to NXF1 and serves as receptor for the RNA export element RTE. It also possess mRNA export activity and can facilitate the access of DEAD-box protein DBP5 to mRNA at the nuclear pore complex (NPC). RNA-binding protein 15B (RBM15B), also termed one twenty-two 3 (OTT3), is a paralog of RBM15 and therefore has post-transcriptional regulatory activity. It is a nuclear protein sharing with RBM15 the association with the splicing factor compartment and the nuclear envelope as well as the binding to mRNA export factors NXF1 and Aly/REF. Members in this family belong to the Spen (split end) protein family, which share a domain architecture comprising of three N-terminal RNA recognition motifs (RRMs), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a C-terminal SPOC (Spen paralog and ortholog C-terminal) domain.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 530371379  830 VGGLCPSVSEADLRSHFQKY-QVSEISIYDSTNYRYASLAFTKNSDAKIAVKEMngIEINGKSVNVWPVKI 899
Cdd:cd12309     7 VGNLEITITEEELRRAFERYgVVEDVDIKRPPRGQGNAYAFVKFLNLDMAHRAK--VAMSGQYIGRNQIKI 75

RNA recognition motif (RRM) found in nucleolar protein 8 (NOL8) and similar proteins; This model corresponds to the RRM of NOL8 (also termed Nop132) encoded by a novel NOL8 gene that is up-regulated in the majority of diffuse-type, but not intestinal-type, gastric cancers. Thus, NOL8 may be a good molecular target for treatment of diffuse-type gastric cancer. Also, NOL8 is a phosphorylated protein that contains an N-terminal RNA recognition motif (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), suggesting NOL8 is likely to function as a novel RNA-binding protein. It may be involved in regulation of gene expression at the post-transcriptional level or in ribosome biogenesis in cancer cells.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|...
gi 530371379  828 IHVGGLCPSVSEADLRSHFQKY-QVSEISIYDSTNYRYASLAF 869
Cdd:cd12226     2 LFVGGLSPSITEDDLERRFSRFgTVSDVEIIRKKDAPDRGFAY 44

RNA recognition motif (RRM) found in serine/arginine-rich splicing factor 3 (SRSF3) and similar proteins; This subfamily corresponds to the RRM of two serine/arginine (SR) proteins, serine/arginine-rich splicing factor 3 (SRSF3) and serine/arginine-rich splicing factor 7 (SRSF7). SRSF3, also termed pre-mRNA-splicing factor SRp20, modulates alternative splicing by interacting with RNA cis-elements in a concentration- and cell differentiation-dependent manner. It is also involved in termination of transcription, alternative RNA polyadenylation, RNA export, and protein translation. SRSF3 is critical for cell proliferation, and tumor induction and maintenance. It can shuttle between the nucleus and cytoplasm. SRSF7, also termed splicing factor 9G8, plays a crucial role in both constitutive splicing and alternative splicing of many pre-mRNAs. Its localization and functions are tightly regulated by phosphorylation. SRSF7 is predominantly present in the nuclear and can shuttle between nucleus and cytoplasm. It cooperates with the export protein, Tap/NXF1, helps mRNA export to the cytoplasm, and enhances the expression of unspliced mRNA. Moreover, SRSF7 inhibits tau E10 inclusion through directly interacting with the proximal downstream intron of E10, a clustering region for frontotemporal dementia with Parkinsonism (FTDP) mutations. Both SRSF3 and SRSF7 contain a single N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a C-terminal RS domain rich in serine-arginine dipeptides. The RRM domain is involved in RNA binding, and the RS domain has been implicated in protein shuttling and protein-protein interactions.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 530371379  828 IHVGGLCPSVSEADLRSHFQKYQVSeISIYDSTNYR-YASLAFTKNSDAKIAVKEMNGIEINGKSVNV 894
Cdd:cd12373     2 VYVGNLGPRVTKRELEDAFEKYGPL-RNVWVARNPPgFAFVEFEDPRDAEDAVRALDGRRICGSRVRV 68

RNA recognition motif 2 (RRM2) found in vertebrate RNA-binding protein RBM23, RBM39 and similar proteins; This subfamily corresponds to the RRM2 of RBM39 (also termed HCC1), a nuclear autoantigen that contains an N-terminal arginine/serine rich (RS) motif and three RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). An octapeptide sequence called the RS-ERK motif is repeated six times in the RS region of RBM39. Although the cellular function of RBM23 remains unclear, it shows high sequence homology to RBM39 and contains two RRMs. It may possibly function as a pre-mRNA splicing factor.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 530371379  828 IHVGGLCPSVSEADLRSHFQKY-QVSEISI-YDSTNYR---YASLAFTKNSDAKIAVKEMNGIEINGKSVNVWPV 897
Cdd:cd12284     1 LYVGSLHFNITEDMLRGIFEPFgKIEFVQLqKDPETGRskgYGFIQFRDAEDAKKALEQLNGFELAGRPMKVGHV 75