Immunoglobulin V-set domain; This domain is found in antibodies as well as neural protein P0 and CTL4 amongst others.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 20137696    30 YTSRVLEAVNGTDARLKCTFSSFaPVGDALTVTWNFRPLDGGPEQFVFYYHIDpfQPMsGRFKDRVSWDGNPERYDASIL 109
Cdd:pfam07686   1 QTPREVTVALGGSVTLPCTYSSS-MSEASTSVYWYRQPPGKGPTFLIAYYSNG--SEE-GVKKGRFSGRGDPSNGDGSLT 76

                          90       100       110
                  ....*....|....*....|....*....|....
gi 20137696   110 LWKLQFDDNGTYTCQVkNPPDVDGVIGEIRLSVV 143
Cdd:pfam07686  77 IQNLTLSDSGTYTCAV-IPSGEGVFGKGTRLTVL 109

Immunoglobulin (Ig)-like domain of protein zero (P0) and similar proteins; The members here are composed of the immunoglobulin (Ig) domain of protein zero (P0), a myelin membrane adhesion molecule. P0 accounts for over 50% of the total protein in peripheral nervous system (PNS) myelin. P0 is a single-pass transmembrane glycoprotein with a highly basic intracellular domain and an extracellular Ig domain. The extracellular domain of P0 (P0-ED) is similar to the Ig variable domain, carrying one acceptor sequence for N-linked glycosylation. P0 plays a role in membrane adhesion in the spiral wraps of the myelin sheath. The intracellular domain is thought to mediate membrane apposition of the cytoplasmic faces and may, through electrostatic interactions, interact directly with lipid headgroups. It is thought that homophilic interactions of the P0 extracellular domain mediate membrane juxtaposition in the extracellular space of PNS myelin. This group also contains the Ig domain of sodium channel subunit beta-2 (SCN2B), and of epithelial V-like antigen 1 (EVA). EVA, also known as myelin protein zero-like 2, is an adhesion molecule, which may play a role in structural organization of the thymus and early lymphocyte development. SCN2B subunits play a role in determining sodium channel density and function in neurons,and in control of electrical excitability in the brain.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 20137696  27 VEIYTSRVLEAVNGTDARLKCTFSSFAPVGDALTVTWNFRPLDGGPEQFVFYYH-IDPFQPMSGRFKDRVSWDGNPERYD 105
Cdd:cd05715   1 MEVYTPRELNVLNGSDVRLTCTFTSCYTVGDAFSVTWTYQPEGGNTTESMFHYSkGKPYILKVGRFKDRVSWAGNPSKKD 80

                        90       100       110
                ....*....|....*....|....*....|....*..
gi 20137696 106 ASILLWKLQFDDNGTYTCQVKNPPDVDGVIGEIRLSV 142
Cdd:cd05715  81 ASIVISNLQFSDNGTYTCDVKNPPDIVGGHGEIRLYV 117

Immunoglobulin V-set domain; This domain is found in antibodies as well as neural protein P0 and CTL4 amongst others.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 20137696    30 YTSRVLEAVNGTDARLKCTFSSFaPVGDALTVTWNFRPLDGGPEQFVFYYHIDpfQPMsGRFKDRVSWDGNPERYDASIL 109
Cdd:pfam07686   1 QTPREVTVALGGSVTLPCTYSSS-MSEASTSVYWYRQPPGKGPTFLIAYYSNG--SEE-GVKKGRFSGRGDPSNGDGSLT 76

                          90       100       110
                  ....*....|....*....|....*....|....
gi 20137696   110 LWKLQFDDNGTYTCQVkNPPDVDGVIGEIRLSVV 143
Cdd:pfam07686  77 IQNLTLSDSGTYTCAV-IPSGEGVFGKGTRLTVL 109

Immunoglobulin Variable (V) domain of the Coxsackievirus and Adenovirus Receptor (CAR), and similar proteins; The members here are composed of the Variable (V) domain of the Coxsackievirus and Adenovirus Receptor (CAR), and similar proteins. CAR, which is encoded by human CXADR gene, is a cell adhesion molecule of the Immunoglobulin (Ig) superfamily. The CAR acts as a type I membrane receptor for group B1-B6 coxsackie viruses and subgroup C adenoviruses. For instance, adenovirus interacts with the coxsackievirus and adenovirus receptor to enter epithelial airway cells. The CAR is also shown to be involved in physiological processes such as neuronal and heart development, epithelial tight junction integrity, and tumor suppression. The CAR is a component of the epithelial apical junction complex that may function as a homophilic cell adhesion molecule and is essential for tight junction integrity. The CAR is also involved in transepithelial migration of leukocytes through adhesive interactions with JAML a transmembrane protein of the plasma membrane of leukocytes. The interaction between both receptors also mediates the activation of gamma-delta T-cells, a subpopulation of T-cells residing in epithelia and involved in tissue homeostasis and repair. The CAR is composed of one V-set and one C2-set Ig module, a single transmembrane helix, and an intracellular domain. This group belongs to the V-set of IgSF domains, having A, B, E and D strands in one beta-sheet and A', G, F, C, C' and C" in the other

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 20137696  35 LEAVNGTDARLKCTFSSFAPVGDALTVTWNFRPLDGGPEQFVFYYHIDPFQPMSGRFKDRVSWDGNPERYDASILLWKLQ 114
Cdd:cd20960  10 IKKVAGENVTLPCHHQLGLEDQGTLDIEWLLLPSDKVEKVVITYSGDRVYNHYYPALKGRVAFTSNDLSGDASLNISNLK 89

                        90
                ....*....|....*..
gi 20137696 115 FDDNGTYTCQVKNPPDV 131
Cdd:cd20960  90 LSDTGTYQCKVKKAPGY 106

First immunoglobulin (Ig) variable (V) domain of rat MRC OX-2 antigen, and similar domains; The members here are composed of the first immunoglobulin (Ig) domain of rat MRC OX-2 antigen (also known as CD200) and similar proteins. MRC OX-2 is a membrane glycoprotein expressed in a variety of lymphoid and non-lymphoid cells in rats. It has a similar broad distribution pattern in humans. MRC OX-2 may regulate myeloid cell activity. The protein has an extracellular portion containing two Ig-like domains, a transmembrane portion, and a cytoplasmic portion.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 20137696  33 RVLEAVNGTDARLKCTFSSfapVGDALTVTWNfRPLDGGPEQFVFYY--HIDPFQPmsgRFKDRVSWDgNPERYDASILL 110
Cdd:cd05846   6 GDTRAVLGGNATLSCNLTL---PEEVLQVTWQ-KIKASSPENIVTYSkkYGVKIQP---SYVRRISFT-SSGLNSTSITI 77

                        90       100
                ....*....|....*....|.
gi 20137696 111 WKLQFDDNGTYTCQVKNPPDV 131
Cdd:cd05846  78 WNVTLEDEGCYKCLFNTFPDG 98

First immunoglobulin variable (IgV) domain of nectin-1, and similar domains; The members here are composed of the first immunoglobulin (Ig) domain of nectin-1 (also known as poliovirus receptor related protein 1 (PVRL1) or cluster of differentiation (CD) 111). Nectin-1 belongs to the nectin family comprised of four transmembrane glycoproteins (nectins-1 through -4). 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. In addition nectins heterophilically trans-interact with other CAMs such as nectin-like molecules (Necls), nectin-1 for example, has been shown to trans-interact with Necl-1. Nectins also interact with various other proteins, including the actin filament (F-actin)-binding protein, afadin. Mutation in the human nectin-1 gene is associated with cleft lip/palate ectodermal dysplasia syndrome (CLPED1). Nectin-1 is a major receptor for herpes simplex virus through interaction with the viral envelope glycoprotein D.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 20137696  40 GTDARLKCTFSSFAPVGDALTVTWnfRPLDGGPEQFVFYYHIDPFQPMSGRFKDRVSWDgNPERYDASILLWKLQFDDNG 119
Cdd:cd05886  14 GTDVVLHCSFANPLPSVKITQVTW--QKSTNGSKQNVAIYNPSMGVSVLPPYRERVTFL-NPSFTDGTIRLSRLELEDEG 90

                        90
                ....*....|
gi 20137696 120 TYTCQVKNPP 129
Cdd:cd05886  91 VYICEFATFP 100

First Ig-like domain of Junctional adhesion molecule-1 (JAM1)and similar domains; a member of the V-set of IgSF domains; The members here are composed of the first Ig-like domain of Junctional Adhesion Molecule-1 (JAM1)and similar domains. JAM1 is an immunoglobulin superfamily (IgSF) protein with two Ig-like domains in its extracellular region; it plays a role in the formation of endothelial and epithelial tight junction and acts as a receptor for mammalian reovirus sigma-1. The IgSF is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. The two sheets are linked together by a conserved disulfide bond between B strand and F strand. 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. The first Ig-like domain of JAM1 is a member of the V-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C'-C" in the other.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 20137696  33 RVLEAVNGTDARLKCTFSSFApvgDALTVTWNFrplDGGPEQFVFYYHidpfQPMSGRFKDRVSWDGnperydASILLWK 112
Cdd:cd20946   7 QVVTVVENQEVILSCKTPKKT---SSPRVEWKK---LQRDVTFVVFQN----NKIQGDYKGRAEILG------TNITIKN 70

                        90       100       110
                ....*....|....*....|....*....|..
gi 20137696 113 LQFDDNGTYTCQVKNPPDVDGvIGE--IRLSV 142
Cdd:cd20946  71 VTRSDSGKYRCEVSARSDGQN-LGEvtVTLEV 101

Immunoglobulin variable domain (IgV); The members here are composed of the immunoglobulin variable domain (IgV). The IgV family contains the standard Ig superfamily V-set AGFCC'C"/DEB domain topology, and are components of immunoglobulin (Ig) and T cell receptors. The basic structure of Ig molecules is a tetramer of two light chains and two heavy chains linked by disulfide bonds. In Ig, each chain is composed of one variable domain (IgV) and one or more constant domains (IgC); these names reflect the fact that the variability in sequences is higher in the variable domain than in the constant domain. Within the variable domain, there are regions of even more variability called the hypervariable or complementarity-determining regions (CDRs) which are responsible for antigen binding. A predominant feature of most Ig domains is the disulfide bridge connecting 2 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" strands in the other.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 20137696  31 TSRVLEAVNGTDARLKCTFSSFAPVGdalTVTWnFRPLDGGPEQFVFYYhIDPFQPMSGRFKDRVSWDGNPERYdaSILL 110
Cdd:cd00099   4 SPRSLSVQEGESVTLSCEVSSSFSST---YIYW-YRQKPGQGPEFLIYL-SSSKGKTKGGVPGRFSGSRDGTSS--FSLT 76

                        90
                ....*....|....*.
gi 20137696 111 WK-LQFDDNGTYTCQV 125
Cdd:cd00099  77 ISnLQPEDSGTYYCAV 92

Immunoglobulin (Ig)-like domain of the chondroitin sulfate proteoglycan core protein (CSPG), neurocan; The members here are composed of the immunoglobulin (Ig)-like domain of the chondroitin sulfate proteoglycan core protein (CSPG), neurocan. In CSPGs, the Ig-like domain is followed by hyaluronan (HA)-binding tandem repeats, and a C-terminal region with epidermal growth factor-like, lectin-like, and complement regulatory protein-like domains. Separating these N- and C-terminal regions is a nonhomologous glycosaminoglycan attachment region. In cartilage, the CSPG aggrecan (not included in this group) forms cartilage link protein stabilized aggregates with HA. These aggregates contribute to the tissue's load bearing properties. Unlike aggrecan which is widely distributed in connective tissue and extracellular matrices, neurocan is localized almost exclusively in nervous tissue. Aggregates having other CSPGs substituting for aggrecan may contribute to the structural integrity of many different tissues. Members of the vertebrate HPLN (hyaluronan/HA and proteoglycan binding link) protein family are physically linked adjacent to CSPG genes.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 20137696  45 LKCTFS---SFAPVGDALTVTWNFRPLDGGPEQFVFYYHIDPFQPMSGRFKDRVSWDGNPE-RYDASILLWKLQFDDNGT 120
Cdd:cd05902  17 LPCVFTlppSASSPPEGPRIKWTKLSTSGGQQQRPVLVARDNVVRVAKAFQGRVSLPGYPKnRYNASLVLSRLRYSDSGT 96

                ....*
gi 20137696 121 YTCQV 125
Cdd:cd05902  97 YRCEV 101

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        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 20137696  43 ARLKCTFSSFAPVgdalTVTWNFrplDGGPEQFVFYYHIDPFQPmsgrfkdrvswdgnperyDASILLWKLQFDDNGTYT 122
Cdd:cd00096   1 VTLTCSASGNPPP----TITWYK---NGKPLPPSSRDSRRSELG------------------NGTLTISNVTLEDSGTYT 55

                ....*.
gi 20137696 123 CQVKNP 128
Cdd:cd00096  56 CVASNS 61

Immunoglobulin Variable (IgV) domain of B7-H3, a member of the B7 family of immune checkpoint molecules; The members here are composed of the immunoglobulin variable (IgV) domain of B7-H3 also known as CD276), a member of the B7 family of immune checkpoint molecules. B7-H3 is an important immune checkpoint member of the B7 family and shares homology with other B7 ligands such as programmed death ligand 1 (PD-L1). The B7 family molecules interact with CD28 on T-cells to provide co-stimulatory signals that regulate T-cell activation and T-helper cell differentiation. Although B7-H3 has been shown to have both co-stimulatory and co-inhibitory effects on T-cell responses, the most current studies describe B7-H3 as a T cell inhibitor that promotes tumor aggressiveness and proliferation. Moreover, B7-H3 is highly overexpressed on a wide range of human solid cancers and promotes tumor growth, metastasis, and drug resistance. Thus, B7-H3 expression in tumors often correlates with both negative prognosis and poor clinical outcome in cancer patients. B7-H3 protein contains a predicted signal peptide, V- and C-like Ig domains (IgV and IgC), a transmembrane region, and an intracellular tail.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 20137696  40 GTDARLKCTFS---SFAPvgDALTVTWNFRplDGGPEQFVFYYHIDPFQPMSGRFKDRVSW------DGNperydASILL 110
Cdd:cd20934  12 GTDATLRCSFSpepGFSL--AQLSVFWQLT--DTKQLVHSFTESQDQGRDQGSAYANRTALfpdllaQGN-----ASLRL 82

                        90
                ....*....|....*.
gi 20137696 111 WKLQFDDNGTYTCQVK 126
Cdd:cd20934  83 QRVRVADEGSYTCFVS 98