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 564394309   25 TTVRLSETMTLECVYPL--TDNLTQAEWTKDTGTKKVN--IAVYHPNHNMHIDPNylhRVHFqNATVGFRNMSLSFYNAS 100
Cdd:pfam07686   6 VTVALGGSVTLPCTYSSsmSEASTSVYWYRQPPGKGPTflIAYYSNGSEEGVKKG---RFSG-RGDPSNGDGSLTIQNLT 81

                          90       100
                  ....*....|....*....|....*
gi 564394309  101 EADIGIYTCLFHAFPRGSWEKKIKV 125
Cdd:pfam07686  82 LSDSGTYTCAVIPSGEGVFGKGTRL 106

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 564394309  19 EETLWDTTVR--LSETMTLECVY--PLTDNLTQAEWTKDTGTKKVNIAVYHPNHNMHIDPNYLHRVHFQNATVGFRNMSL 94
Cdd:cd05718    1 QRVQVPTEVTgfLGGSVTLPCSLtsPGTTKITQVTWMKIGAGSSQNVAVFHPQYGPSVPNPYAERVEFLAARLGLRNATL 80

                         90       100       110
                 ....*....|....*....|....*....|...
gi 564394309  95 SFYNASEADIGIYTCLFHAFPRGSWEKKIKVVQ 127
Cdd:cd05718   81 RIRNLRVEDEGNYICEFATFPQGNRQGTTWLRV 113

First immunoglobulin variable (IgV) domain of nectin-3 (also known as poliovirus receptor related protein 3), and similar domains; The members here are composed of the first immunoglobulin (Ig) domain of nectin-3 (also known as poliovirus receptor related protein 3 (PVRL3) or cluster of differentiation (CD) 113). Nectin-3 belongs to the nectin family comprised of four transmembrane glycoproteins (nectins-1 through -4). Nectins are synaptic cell adhesion molecules (CAMs) which participate in adhesion and signaling at various intracellular junctions. Nectins form homophilic cis-dimers, followed by homophilic and heterophilic trans-dimers involved in cell-cell adhesion. For example, during spermatid development, the nectin-3,-2 trans-interaction is required for the formation of Sertoli cell-spermatid junctions in testis, and during morphogenesis of the ciliary body, the nectin-3,-1 trans-interaction is important for apex-apex adhesion between the pigment and non-pigment layers of the ciliary epithelia. Nectins also heterophilically trans-interact with other CAMs such as nectin-like molecules (Necls); nectin-3 for example, trans-interacts with Necl-5, regulating cell movement and proliferation. Other proteins with which nectin-3 interacts include the actin filament-binding protein, afadin, integrin alpha-beta3, Par-3, and PDGF receptor; its interaction with PDGF receptor regulates the latter's signaling for anti-apoptosis.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 564394309  26 TVRLSETMTLECVYPLTDNLTQAEWTKDTGTKKVNIAVYHPNHNMHIDPNYLHRVHFQNATVgfRNMSLSFYNASEADIG 105
Cdd:cd05887   10 TAVWGKNVSLKCLIEVNETITQISWEKIHGKSSQTVAVHHPQYGISIQGEYQGRVSFKNYSL--NDATITLHNVGFSDSG 87

                         90       100
                 ....*....|....*....|
gi 564394309 106 IYTCLFHAFPRGSWEKKIKV 125
Cdd:cd05887   88 KYICKAVTFPLGNAQSSTTV 107

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 564394309  22 LWDTTVRLSETMTLECvYPLTDN----LTQAEWTK-DTGTkkvNIAVYHPNHNmhidPNYLH--RVHFQNATVG--FRNM 92
Cdd:cd20989    6 PPEVRGFLGGSVTLPC-HLLPPNmvthVSQVTWQRhDEHG---SVAVFHPKQG----PSFPEseRLSFVAARLGaeLRNA 77

                         90       100
                 ....*....|....*....|....*.
gi 564394309  93 SLSFYNASEADIGIYTCLFHAFPRGS 118
Cdd:cd20989   78 SLAMFGLRVEDEGNYTCEFATFPQGS 103

First immunoglobulin (Ig) domain of nectin-4, and similar domains; The members here are composed of the first immunoglobulin (Ig) domain of nectin-4 (also known as poliovirus receptor related protein 4 or LNIR receptor). Nectin-4 belongs to the nectin family, which is comprised of four transmembrane glycoproteins (nectins-1 through -4). Nectins are synaptic cell adhesion molecules (CAMs) which participate in adhesion and signaling at various intracellular junctions. Nectins form homophilic cis-dimers, followed by homophilic and heterophilic trans-dimers involved in cell-cell adhesion. For example nectin-4 trans-interacts with nectin-1. Nectin-4 has also been shown to interact with the actin filament-binding protein, afadin. Unlike the other nectins, which are widely expressed in adult tissues, nectin-4 is mainly expressed during embryogenesis, and is not detected in normal adult tissue or in serum. Nectin-4 is re-expressed in breast carcinoma, and patients having metastatic breast cancer have a circulating form of nectin-4 formed from the ectodomain

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 564394309  26 TVRLSETMTLECVYPLTDNLT--QAEWTK-DTGTKKVNIAVYHPNHNMHIDPNYLHRVHFQnATVGFRNMSLSFYNASEA 102
Cdd:cd05888    4 TVVLGQDAKLPCFYRGDSGEQvgQVAWARvDAGEGAQEIALLHSKYGLHVFPAYEGRVEQP-PPPRPADGSVLLRNAVQA 82

                         90       100
                 ....*....|....*....|...
gi 564394309 103 DIGIYTCLFHAFPRGSWEKKIKV 125
Cdd:cd05888   83 DEGEYECRVSTFPAGNFQAELRL 105