CD80-like C2-set immunoglobulin domain; These domains belong to the immunoglobulin superfamily.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 383872884  137 PEIVSKALFLETEQLKKLGDCISEDSYPDGNITWYRNGKVLhplegaVVIIFKKEMDPVTQLYTMTSTLEYKTTKADIQM 216
Cdd:pfam08205   1 PTIEPPASLLEGEGPEVVATCSSAGGKPAPRITWYLDGKPL------EAAETSSEQDPESGLVTVTSELKLVPSRSDHGQ 74

                          90
                  ....*....|....*
gi 383872884  217 PFTCSVTYYGPSGQK 231
Cdd:pfam08205  75 SLTCQVSYGALRGSI 89

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 383872884  415 KPQIKMTKK--TDPSGLSKTIICHVEGFPKPAIQWTItgSGSVINQTEESPYINGRYYSKIIIS---PEENVTLTCTAEN 489
Cdd:pfam13927   1 KPVITVSPSsvTVREGETVTLTCEATGSPPPTITWYK--NGEPISSGSTRSRSLSGSNSTLTISnvtRSDAGTYTCVASN 78

Immunoglobulin like; IG domains that cannot be classified into one of IGv1, IGc1, IGc2, IG.

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 383872884   339 SGEVTRQIGDALPVSCTISASRNATVVWMK---------DNIRLRSSPSFSSLH-----YQDAGNYVCE 393
Cdd:smart00410   1 PPSVTVKEGESVTLSCEASGSPPPEVTWYKqggkllaesGRFSVSRSGSTSTLTisnvtPEDSGTYTCA 69

CD80-like C2-set immunoglobulin domain; These domains belong to the immunoglobulin superfamily.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 383872884  137 PEIVSKALFLETEQLKKLGDCISEDSYPDGNITWYRNGKVLhplegaVVIIFKKEMDPVTQLYTMTSTLEYKTTKADIQM 216
Cdd:pfam08205   1 PTIEPPASLLEGEGPEVVATCSSAGGKPAPRITWYLDGKPL------EAAETSSEQDPESGLVTVTSELKLVPSRSDHGQ 74

                          90
                  ....*....|....*
gi 383872884  217 PFTCSVTYYGPSGQK 231
Cdd:pfam08205  75 SLTCQVSYGALRGSI 89

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 383872884  250 TIQVLPPKTAIKEGDNVTLKCLGNGNPPPeEFLFYLPGQPEG---------IRSSNTYTLTDVRRNATGDYKC 313
Cdd:pfam13927   3 VITVSPSSVTVREGETVTLTCEATGSPPP-TITWYKNGEPISsgstrsrslSGSNSTLTISNVTRSDAGTYTC 74

Immunoglobulin V-Type;

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 383872884    38 TIIMPCRLDVPQN-LMFGKWKYEKPDGSPVFIAFRSStkKSVQYDDvPEYKDRLSLSEN-----YTLSISNARISDEKRF 111
Cdd:smart00406   1 SVTLSCKFSGSTFsSYYVSWVRQPPGKGLEWLGYIGS--NGSSYYQ-ESYKGRFTISKDtskndVSLTISNLRVEDTGTY 77

                   ..
gi 383872884   112 VC 113
Cdd:smart00406  78 YC 79

First immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs), and similar domains; The members here are composed of the first immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs). Interactions between IgG and FcgammaR are important to the initiation of cellular and humoral response. IgG binding to FcgammaR leads to a cascade of signals and ultimately to functions such as antibody-dependent-cellular-cytotoxicity (ADCC), endocytosis, phagocytosis, release of inflammatory mediators, etc. FcgammaR has two Ig-like domains. This group also contains FcepsilonRI which binds IgE with high affinity.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 383872884 255 PPKTAIKEGDNVTLKCLGNGNPPPEEFLFYLPGQ--PEgirSSNTYTLTDVRRNATGDYKC 313
Cdd:cd05752    7 PPWTTVFQGEKVTLTCQGFYSPEQNSTQWYHNGTliSS---TSSSYRIVAATVNDSGEYRC 64

Immunoglobulin like; IG domains that cannot be classified into one of IGv1, IGc1, IGc2, IG.

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 383872884   339 SGEVTRQIGDALPVSCTISASRNATVVWMK---------DNIRLRSSPSFSSLH-----YQDAGNYVCE 393
Cdd:smart00410   1 PPSVTVKEGESVTLSCEASGSPPPEVTWYKqggkllaesGRFSVSRSGSTSTLTisnvtPEDSGTYTCA 69

First immunoglobulin variable (IgV) domain of poliovirus receptor (PVR, also known as CD155 and necl-5), and similar domains; The members here are composed of the first immunoglobulin (Ig) domain of poliovirus receptor (PVR, also known as CD155 and nectin-like protein 5 (necl-5)). Poliovirus (PV) binds to its cellular receptor (PVR/CD155) to initiate infection. CD155 is a membrane-anchored, single-span glycoprotein; its extracellular region has three Ig-like domains. There are four different isotypes of CD155 (referred to as alpha, beta, gamma, and delta), that result from alternate splicing of the CD155 mRNA, and have identical extracellular domains. CD155-beta and CD155-gamma are secreted; CD155-alpha and CD155-delta are membrane-bound and function as PV receptors. The virus recognition site is contained in the amino-terminal domain, D1. Having the virus attachment site on the receptor distal from the plasma membrane may be important for successful initiation of infection of cells by the virus. CD155 binds in the poliovirus "canyon" with a footprint similar to that of the intercellular adhesion molecule-1 receptor on human rhinoviruses. This group also includes the first Ig-like domain of nectin-1 (also known as poliovirus receptor related protein(PVRL)1; CD111), nectin-3 (also known as PVRL 3), nectin-4 (also known as PVRL4; LNIR receptor)and DNAX accessory molecule 1 (DNAM-1; CD226).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 383872884  29 YTVNSAYGDTIIMPCRLDVPQNLMFGKWKYEKPDG--SPVFIAFRSSTKKSVQyddvPEYKDRLSL------SENYTLSI 100
Cdd:cd05718    7 TEVTGFLGGSVTLPCSLTSPGTTKITQVTWMKIGAgsSQNVAVFHPQYGPSVP----NPYAERVEFlaarlgLRNATLRI 82

                         90
                 ....*....|....*..
gi 383872884 101 SNARISDEKRFVCMLVT 117
Cdd:cd05718   83 RNLRVEDEGNYICEFAT 99

CD80-like C2-set immunoglobulin domain; These domains belong to the immunoglobulin superfamily.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 383872884  137 PEIVSKALFLETEQLKKLGDCISEDSYPDGNITWYRNGKVLhplegaVVIIFKKEMDPVTQLYTMTSTLEYKTTKADIQM 216
Cdd:pfam08205   1 PTIEPPASLLEGEGPEVVATCSSAGGKPAPRITWYLDGKPL------EAAETSSEQDPESGLVTVTSELKLVPSRSDHGQ 74

                          90
                  ....*....|....*
gi 383872884  217 PFTCSVTYYGPSGQK 231
Cdd:pfam08205  75 SLTCQVSYGALRGSI 89

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 383872884  250 TIQVLPPKTAIKEGDNVTLKCLGNGNPPPeEFLFYLPGQPEG---------IRSSNTYTLTDVRRNATGDYKC 313
Cdd:pfam13927   3 VITVSPSSVTVREGETVTLTCEATGSPPP-TITWYKNGEPISsgstrsrslSGSNSTLTISNVTRSDAGTYTC 74

Immunoglobulin V-Type;

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 383872884    38 TIIMPCRLDVPQN-LMFGKWKYEKPDGSPVFIAFRSStkKSVQYDDvPEYKDRLSLSEN-----YTLSISNARISDEKRF 111
Cdd:smart00406   1 SVTLSCKFSGSTFsSYYVSWVRQPPGKGLEWLGYIGS--NGSSYYQ-ESYKGRFTISKDtskndVSLTISNLRVEDTGTY 77

                   ..
gi 383872884   112 VC 113
Cdd:smart00406  78 YC 79

First immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs), and similar domains; The members here are composed of the first immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs). Interactions between IgG and FcgammaR are important to the initiation of cellular and humoral response. IgG binding to FcgammaR leads to a cascade of signals and ultimately to functions such as antibody-dependent-cellular-cytotoxicity (ADCC), endocytosis, phagocytosis, release of inflammatory mediators, etc. FcgammaR has two Ig-like domains. This group also contains FcepsilonRI which binds IgE with high affinity.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 383872884 255 PPKTAIKEGDNVTLKCLGNGNPPPEEFLFYLPGQ--PEgirSSNTYTLTDVRRNATGDYKC 313
Cdd:cd05752    7 PPWTTVFQGEKVTLTCQGFYSPEQNSTQWYHNGTliSS---TSSSYRIVAATVNDSGEYRC 64

Immunoglobulin domain; The members here are composed of the immunoglobulin (Ig) domain found in the Ig superfamily. The Ig superfamily is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. Members of this group are components of immunoglobulin, neuroglia, cell surface glycoproteins, including T-cell receptors, CD2, CD4, CD8, and membrane glycoproteins, including butyrophilin and chondroitin sulfate proteoglycan core protein. A predominant feature of most Ig domains is a disulfide bridge connecting the two beta-sheets with a tryptophan residue packed against the disulfide bond. Ig superfamily (IgSF) domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Typically, the V-set domains have A, B, E, and D strands in one sheet and A', G, F, C, C' and C" in the other. The structures in C1-set are smaller than those in the V-set; they have one beta sheet that is formed by strands A, B, E, and D and the other by strands G, F, C, and C'. Moreover, a C1-set Ig domain contains a short C' strand (three residues) and lacks A' and C" strand. Unlike other Ig domain sets, C2-set structures do not have a D strand. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 383872884 432 TIICHVEGFPKPAIQWTItgSGSVINQTEESPYINGRYYSKIIIS---PEENVTLTCTAENQLERTVNS 497
Cdd:cd00096    2 TLTCSASGNPPPTITWYK--NGKPLPPSSRDSRRSELGNGTLTISnvtLEDSGTYTCVASNSAGGSASA 68

Second immunoglobulin (Ig)-like domain of a Follistatin-related protein 5, and similar domains; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the second immunoglobulin (Ig)-like domain found in human Follistatin-related protein 5 (FSTL5) and a follistatin-like molecule encoded by the CNS-related Mahya gene. Mahya genes have been retained in certain Bilaterian branches during evolution. They are conserved in Hymenoptera and Deuterostomes, but are absent from other metazoan species such as fruit fly and nematode. Mahya proteins are secretory, with a follistatin-like domain (Kazal-type serine/threonine protease inhibitor domain and EF-hand calcium-binding domain), two Ig-like domains, and a novel C-terminal domain. Mahya may be involved in learning and memory and in processing of sensory information in Hymenoptera and vertebrates. Follistatin is a secreted, multidomain protein that binds activins with high affinity and antagonizes their signaling.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 383872884 416 PQIKMTKKTDPS--GLSKTIICHVEGFPKPAIQWTITGSGSVINQTEESPYI-NGryySKIIISP---EENVTLTCTAEN 489
Cdd:cd05736    1 PVIRVYPEFQAKepGVEASLRCHAEGIPLPRVQWLKNGMDINPKLSKQLTLIaNG---SELHISNvryEDTGAYTCIAKN 77

                         90
                 ....*....|...
gi 383872884 490 Q--LERTVNSLNV 500
Cdd:cd05736   78 EggVDEDISSLFV 90

Immunoglobulin domain; This domain contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 383872884  336 LNPSGEVTRQiGDALPVSCTISASRNATVVWMKDNIRLRSSPSF--SSLHYQDAGNYVCETALQevEGLKKRESLTLIV 412
Cdd:pfam13895   4 LTPSPTVVTE-GEPVTLTCSAPGNPPPSYTWYKDGSAISSSPNFftLSVSAEDSGTYTCVARNG--RGGKVSNPVELTV 79

Second immunoglobulin (Ig)-like domain of Kirrel (kin of irregular chiasm-like) 3, and similar domains; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the second immunoglobulin (Ig)-like domain of Kirrel (kin of irregular chiasm-like) 3 (also known as Neph2). This protein has five Ig-like domains, one transmembrane domain, and a cytoplasmic tail. Included in this group is mammalian Kirrel (Neph1), Kirrel2 (Neph3), and Drosophila RST (irregular chiasm C-roughest) protein. These proteins contain multiple Ig domains, have properties of cell adhesion molecules, and are important in organ development.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 383872884 157 CISEDSYPDGNITWYRNGKvlhPLEGAVviiFKKEMDPVTQLYTMTSTLEYKTTKADIQMPFTCSVTYYG-PSGQKT 232
Cdd:cd05759   22 CRARGAKPAAEIIWFRDGE---QLEGAV---YSKELLKDGKRETTVSTLLITPSDLDTGRTFTCRARNEAiPNGKET 92

Immunoglobulin constant (IgC)-like domain of antigen receptor Cluster of Differentiation (CD) 80; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin constant (IgC)-like domain of the antigen receptor Cluster of Differentiation (CD) 80. CD80 (also known as glycoprotein B7-1) and CD86 (also known as glycoprotein B7-2) are expressed on antigen-presenting cells and deliver the co-stimulatory signal through CD28 and CTLA-4 (CD152) on T cells. signaling through CD28 augments the T-cell response, whereas CTLA-4 signaling attenuates it. CD80 contains two Ig-like domains, an amino-terminal immunoglobulin variable (IgV)-like domain characteristic of adhesion molecules, and a membrane proximal immunoglobulin constant (IgC)-like domain similar to the constant domains of antigen receptors. Members of the Ig family are components of immunoglobulin, T-cell receptors, CD1 cell surface glycoproteins, secretory glycoproteins A/C, and major histocompatibility complex (MHC) class I/II molecules. In immunoglobulins, each chain is composed of one variable domain (IgV) and one or more IgC domains. These names reflect the fact that the variability in sequences is higher in the variable domain than in the constant domain. The IgV domain is responsible for antigen binding, and the IgC domain is involved in oligomerization and molecular interactions.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 383872884 157 CISEDSYPDGNITWYRNGKVLHPLEGAVViifkkeMDPVTQLYTMTSTLEYKTTKadiQMPFTCSVTYygpsGQKTV 233
Cdd:cd16083   21 CSTSGGFPEPRLSWLENGEELNAINTTVS------QDPETELYTVSSELDFNVTY---NHSIVCLIKY----GDSRV 84

First immunoglobulin variable (IgV) domain of nectin-2, nectin-like protein 5, and similar domains; The members here are composed of the second immunoglobulin (Ig) domain of nectin-2 (also known as poliovirus receptor related protein 2 or Cluster of Differentiation 112 (CD112)), nectin-like protein 5 (CD155), and similar proteins. Nectins and Nectin-like molecules are a family of Ca(2+)-independent immunoglobulin-like transmembrane glycoproteins belonging to the class of adhesion receptors, consisting of nine members (nectins 1 through 4 and nectin-like proteins 1 through 5). Nectins are synaptic cell adhesion molecules (CAMs) which facilitate adhesion and signaling at various intracellular junctions. Nectins form homophilic cis-dimers, followed by homophilic and heterophilic trans-dimers involved in cell-cell adhesion. Nectin-2 and nectin-3 localize at Sertoli-spermatid junctions where they form heterophilic trans-interactions between the cells that are essential for the formation and maintenance of the junctions and for spermatid development. CD155 is the fifth member in the nectin-like molecule family, and functions as the receptor of poliovirus; therefore, CD155 is also referred to as Necl-5, or PVR. In contrast to all other family members, CD155 lacks self-adhesion capacity, yet it shares with nectins the feature to interact with other nectins. For instance, CD155 heterophilically trans-interacts with nectin-3, thereby contributing significantly to the establishment of adherens junctions between epithelial cells. This group belongs to the Constant 1 (C1)-set of IgSF domains, which has one beta-sheet that is formed by strands A-B-E-D and the other strands by G-F-C-C'.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 383872884  29 YTVNSAYGDTIIMPCRLDVPQN-LMFGKWKYEKPDGSPVFIAFRSStkksvQYDDVPEyKDRLSLS--------ENYTLS 99
Cdd:cd20989    7 PEVRGFLGGSVTLPCHLLPPNMvTHVSQVTWQRHDEHGSVAVFHPK-----QGPSFPE-SERLSFVaarlgaelRNASLA 80

                         90
                 ....*....|....*...
gi 383872884 100 ISNARISDEKRFVCMLVT 117
Cdd:cd20989   81 MFGLRVEDEGNYTCEFAT 98

Second immunoglobulin (Ig)-like domain of the nectin-like molecules Necl-1 - Necl-4; member of the I-set of Ig superfamily domains; The members here are composed of the second immunoglobulin (Ig)-like domain of the nectin-like molecules Necl-1 (also known as cell adhesion molecule 3 or CADM3), Necl-2 (also known as CADM1), Necl-3 (also known as CADM2) and Necl-4 (also known as CADM4). These nectin-like molecules have similar domain structures to those of nectins. At least five nectin-like molecules have been identified (Necl-1 through Necl-5). These have an extracellular region containing three Ig-like domains, one transmembrane region, and one cytoplasmic region. The N-terminal Ig-like domain of the extracellular region belongs to the V-type subfamily of Ig domains, is essential to cell-cell adhesion, and plays a part in the interaction with the envelope glycoprotein D of various viruses. Necl-1 and Necl-2 have Ca(2+)-independent homophilic and heterophilic cell-cell adhesion activity. Necl-1 is specifically expressed in neural tissue and is important to the formation of synapses, axon bundles, and myelinated axons. Necl-2 is expressed in a wide variety of tissues, and is a putative tumour suppressor gene, which is downregulated in aggressive neuroblastoma. Necl-3 has been shown to accumulate in tissues of the central and peripheral nervous system, where it is expressed in ependymal cells and myelinated axons. It is observed at the interface between the axon shaft and the myelin sheath. Necl-4 is expressed on Schwann cells, and plays a key part in initiating peripheral nervous system (PNS) myelination. Necl-4 participates in cell-cell adhesion and is proposed to play a role in tumor suppression.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 383872884 134 PSKPEI-VSKALFLETEQLKKlgDCISEDSYPDGNITWYRNGKVLHPLEgavviifKKEMDPVTQLYTMTSTLEYKTTKA 212
Cdd:cd05761    4 PEKPVItGFTSPVVEGDEITL--TCTTSGSKPAADIRWFKNDKELKGVK-------EVQESGAGKTFTVTSTLRFRVDRD 74

                         90
                 ....*....|
gi 383872884 213 DIQMPFTCSV 222
Cdd:cd05761   75 DDGVAVICRV 84

Signal-regulatory protein (SIRP) immunoglobulin-like domain 2; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin (Ig)-like domain in Signal-Regulatory Protein (SIRP), domain 2 (C1 repeat 1). The SIRPs belong to the "paired receptors" class of membrane proteins that comprise several genes coding for proteins with similar extracellular regions, but very different transmembrane/cytoplasmic regions with different (activating or inhibitory) signaling potentials. They are commonly on NK cells, but are also on many myeloid cells. Their extracellular region contains three Immunoglobulin superfamily domains, a single V-set and two C1-set IgSF domains. Their cytoplasmic tails contain either ITIMs or transmembrane regions that have positively charged residues that allow an association with adaptor proteins, such as DAP12/KARAP, containing ITAMs. There are 3 distinct SIRP members: alpha, beta, and gamma. SIRP alpha (also known as CD172a or SRC homology 2 domain-containing protein tyrosine phosphatase substrate 1/Shps-1) is a membrane receptor that interacts with a ligand CD47 expressed on many cells and gives an inhibitory signal through immunoreceptor tyrosine-based inhibition motifs in the cytoplasmic region that interact with phosphatases SHP-1 and SHP-2. SIRP beta has a short cytoplasmic region and associates with a transmembrane adapter protein DAP12 containing immunoreceptor tyrosine-based activation motifs to give an activating signal. SIRP gamma contains a very short cytoplasmic region lacking obvious signaling motifs, but also binds CD47, but with much less affinity.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 383872884 157 CISEDSYP-DGNITWYRNGKVLHPLEGAVviifKKEMDPVTqlYTMTSTLEYKTTKADIQMPFTCSV 222
Cdd:cd05772   24 CKSHGFSPrDITLKWFKNGNELSALQTTV----FPEGDSVS--YSVSSTVQVVLTKDDVHSQLTCEV 84

Immunoglobulin I-set domain;

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 383872884  251 IQVLPPKTAIKEGDNVTLKCLGNGNPPPeEFLFYLPGQPegIRSS---------NTYTLT--DVRRNATGDYKC 313
Cdd:pfam07679   3 FTQKPKDVEVQEGESARFTCTVTGTPDP-EVSWFKDGQP--LRSSdrfkvtyegGTYTLTisNVQPDDSGKYTC 73