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 259490321   37 LLARVGGQAELSCQVIPPHSVMHMEVRWFR----SGHSQPVYLYRGGHKMseeaaPEYANRTEFvKEAIGEGKVSLRIYN 112
Cdd:pfam07686   6 VTVALGGSVTLPCTYSSSMSEASTSVYWYRqppgKGPTFLIAYYSNGSEE-----GVKKGRFSG-RGDPSNGDGSLTIQN 79

                          90       100       110
                  ....*....|....*....|....*....|
gi 259490321  113 INILDDGPYQCS-FNDSGFIDVAIMNLNVT 141
Cdd:pfam07686  80 LTLSDSGTYTCAvIPSGEGVFGKGTRLTVL 109

Immunoglobulin Variable (IgV) domain of B7-H4; The members here are composed of the immunoglobulin variable (IgV) domain of B7-H4 (also known as B7-S1, B7x, or Vtcn1). B7-H4 is one of the B7 family of immune-regulatory ligands that act as negative regulators of T cell function; it contains one IgV domain and one IgC domain. The B7-family consists of structurally related cell-surface protein ligands, which bind to receptors on lymphocytes that regulate immune responses. The binding of B7-H4 to unidentified receptors results in the inhibition of TCR-mediated T cell proliferation, cell-cycle progression and IL-2 production. As a co-inhibitory molecule, B7-H4 is widely expressed in tumor tissues and its expression is significantly associated with poor prognosis in human cancers such as glioma, pancreatic cancer, oral squamous cell carcinoma, renal cell carcinoma, and lung cancer.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 259490321  31 TTPTRHLLARVGGQAELSCQVIPPHSVMHMEVRWFRSGHSQPVYLYRGGHKMSEEAAPEYANRTEFVKEAIGEGKVSLRI 110
Cdd:cd20984    1 TVTAKHLAGNIGEDGILSCTFTPDIKLSDIVIQWLKEGDSGLVHEFKEGKDELSRQSPMFRGRTSLFADQVHVGNASLRL 80

                         90
                 ....*....|....*...
gi 259490321 111 YNINILDDGPYQCSFNDS 128
Cdd:cd20984   81 KNVQLTDAGTYLCIISNS 98

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 259490321  29 RVTTPTrHLLARVGGQAELSCQVIPPHSVMHMEVRWFR--SGHSQPVYLYRGGHKMSEEAapEYANRTEFVKEAIGEGKV 106
Cdd:cd05718    2 RVQVPT-EVTGFLGGSVTLPCSLTSPGTTKITQVTWMKigAGSSQNVAVFHPQYGPSVPN--PYAERVEFLAARLGLRNA 78

                         90
                 ....*....|....*....
gi 259490321 107 SLRIYNINILDDGPYQCSF 125
Cdd:cd05718   79 TLRIRNLRVEDEGNYICEF 97

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 259490321  33 PTRHLLARVGGQAELSCQVIPPH--SVMHMEVRWFRSGHSQPVYLYRGGHKMSEEAAPEYANRTEFVKEAIGEGKVSLRI 110
Cdd:cd20934    3 PEDPVVALVGTDATLRCSFSPEPgfSLAQLSVFWQLTDTKQLVHSFTESQDQGRDQGSAYANRTALFPDLLAQGNASLRL 82

                         90       100       110
                 ....*....|....*....|....*....|..
gi 259490321 111 YNINILDDGPYQCSFNDSGFiDVAIMNLNVTA 142
Cdd:cd20934   83 QRVRVADEGSYTCFVSVQDF-GSAAVSLQVAA 113

Immunoglobulin variable domain (IgV) in Cluster of Differentiation (CD) 86; The members here are composed of the immunoglobulin variable region (IgV) in the Cluster of Differentiation (CD) 86). Glycoproteins B7-1 (also known as cluster of differentiation (CD) 80) and B7-2 (also known as CD86) are expressed on antigen-presenting cells and deliver the co-stimulatory signal through CD28 and CTLA-4 (also known as CD152) on T cells. signaling through CD28 augments the T-cell response, whereas CTLA-4 signaling attenuates it. The CTLA-4 and B7-2 monomers are both two-layer beta-sandwiches that display the chain topology characteristic of the immunoglobulin variable (V-type) domains present in antigen receptors. The front and back sheets of B7-2 are composed of AGFCC'C" and BED strands, respectively. Members of the IgV family 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.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 259490321  36 HLLARVGGQAELSCQVIPPH--SVMHMEVRWfRSGHSQPVY-LYRGGHKmSEEAAPEYANRTEFVKEaigegKVSLRIYN 112
Cdd:cd16087    2 KIQAYFNETAYLPCQFKNPQniSLSELVVFW-QDQKKLVLYeLYLGKEK-LDNVNSKYIGRTSFDQE-----NWTLQLHN 74

                         90
                 ....*....|.
gi 259490321 113 INILDDGPYQC 123
Cdd:cd16087   75 VQIKDQGTYQC 85

Immunoglobulin V-Type;

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 259490321    45 AELSCQViPPHSVMHMEVRWFRSGHSQPVY-LYRGGHKMSEEAAPEYANRTEFVKEAiGEGKVSLRIYNINILDDGPYQC 123
Cdd:smart00406   2 VTLSCKF-SGSTFSSYYVSWVRQPPGKGLEwLGYIGSNGSSYYQESYKGRFTISKDT-SKNDVSLTISNLRVEDTGTYYC 79

                   ..
gi 259490321   124 SF 125
Cdd:smart00406  80 AV 81

First immunoglobulin variable (IgV) domain of DNAX accessory molecule 1, and similar domains; The members here are composed of the first immunoglobulin (Ig) domain of DNAX accessory molecule 1 (DNAM-1, also known as CD226). DNAM-1 is a transmembrane protein having two Ig-like domains. It is an adhesion molecule which plays a part in tumor-directed cytotoxicity and adhesion in natural killer (NK) cells and T lymphocytes. It has been shown to regulate the NK cell killing of several tumor types, including myeloma cells and ovarian carcinoma cells. DNAM-1 interacts specifically with poliovirus receptor (PVR; CD155) and nectin -2 (CD211), other members of the Ig superfamily. DNAM-1 is expressed in most peripheral T cells, NK cells, monocytes and a subset of B lymphocytes.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 259490321  61 EVRWFR-SGHSQPVYLYRGGHKMSEEaaPEYANRTEFVKEAIGEGKVSLRIYNINILDDGPYQCSF 125
Cdd:cd05889   31 QVEWTKiGGQKDNIAVYHPTHGMHIR--KPYAGRVYFLNSTMASNNMSLSFRNASEDDVGYYSCSL 94