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

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 768005958   38 IEALPSSAAEGKDVLLLaC----NISETIQAYYWHKGKTAEG-SPLIAGYITDIQANIPGAAYSGRETV-YPNGSLLFQN 111
Cdd:pfam07686   1 QTPREVTVALGGSVTLP-CtyssSMSEASTSVYWYRQPPGKGpTFLIAYYSNGSEEGVKKGRFSGRGDPsNGDGSLTIQN 79

                          90       100       110
                  ....*....|....*....|....*....|
gi 768005958  112 ITLEDAGSYTLRTINASYDSDQATGQLHVH 141
Cdd:pfam07686  80 LTLSDSGTYTCAVIPSGEGVFGKGTRLTVL 109

Immunoglobulin (Ig)-like domain of carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) and similar proteins; The members here are composed of the immunoglobulin (Ig)-like domain in carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) and related domains. The CEA family is a group of anchored or secreted glycoproteins, expressed by epithelial cells, leukocytes, endothelial cells and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. This group represents the CEACAM subfamily. CEACAM1 has many important cellular functions: it is a cell adhesion molecule and a signaling molecule that regulates the growth of tumor cells, an angiogenic factor, and a receptor for bacterial and viral pathogens, including mouse hepatitis virus (MHV). In mice, four isoforms of CEACAM1 generated by alternative splicing have either two (D1, D4) or four (D1-D4) Ig-like domains on the cell surface. This family corresponds to the D1 Ig-like domain. Also belonging to this group is the N-terminal immunoglobulin (Ig)-like domain of the signaling lymphocyte activation molecule (SLAM) family, CD84-like family. The SLAM family is a group of immune-cell specific receptors that can regulate both adaptive and innate immune responses. SLAM family proteins are organized as an extracellular domain with having two or four Ig-like domains, a single transmembrane segment, and a cytoplasmic region having Tyr-based motifs. The extracellular domain is organized as a membrane-distal Ig variable (IgV) domain that is responsible for ligand recognition and a membrane-proximal truncated Ig constant-2 (IgC2) domain.

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                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 768005958  44 SAAEGKDVLLLACNISETIQAYYWHKGKTAEGSPLIAGYITDIQANIPGAAYSGRETVYPNGSLLFQNITLEDAGSYTLR 123
Cdd:cd05741    6 YGAEGKNVLLLVPNLQTPLKSVSWYKGKQVSRNDEIAEYENSSDEFRAGSAFSGREYIYTNGSLLIQNITLSDTGFYTLE 85

                         90
                 ....*....|....*..
gi 768005958 124 TINASYDSDQATGQLHV 140
Cdd:cd05741   86 STNIGGKTESATFQLHV 102

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.

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                 ....*....|....*....|....*....|....*....|....*.
gi 768005958  90 IPGAAYSGRETVYPNGSLLFQNITLEDAGSYTLRTINASYDSDQAT 135
Cdd:cd00096   24 LPPSSRDSRRSELGNGTLTISNVTLEDSGTYTCVASNSAGGSASAS 69

Fifth immunoglobulin (Ig) domain of contactin; The members here are composed of the fifth immunoglobulin (Ig) domain of contactins. Contactins are neural cell adhesion molecules and are comprised of six Ig domains followed by four fibronectin type III (FnIII) domains anchored to the membrane by glycosylphosphatidylinositol. The first four Ig domains form the intermolecular binding fragment, which arranges as a compact U-shaped module via contacts between Ig domains 1 and 4, and between Ig domains 2 and 3. Contactin-2 (TAG-1, axonin-1) may play a part in the neuronal processes of neurite outgrowth, axon guidance and fasciculation, and neuronal migration. This group also includes contactin-1 and contactin-5. The different contactins show different expression patterns in the central nervous system. During development and in adulthood, contactin-2 is transiently expressed in subsets of central and peripheral neurons. Contactin-5 is expressed specifically in the rat postnatal nervous system, peaking at about 3 weeks postnatal, and a lack of contactin-5 (NB-2) results in an impairment of neuronal activity in the rat auditory system. Contactin-5 is highly expressed in the adult human brain in the occipital lobe and in the amygdala. Contactin-1 is differentially expressed in tumor tissues and may, through a RhoA mechanism, facilitate invasion and metastasis of human lung adenocarcinoma.

                         10        20        30
                 ....*....|....*....|....*....|.
gi 768005958  96 SGRETVYPNGSLLFQNITLEDAGSYTLRTIN 126
Cdd:cd04969   46 SSRICILPDGSLKIKNVTKSDEGKYTCFAVN 76

Immunoglobulin domain of human Synaptic Adhesion-Like Molecule 5 (SALM5) and similar proteins; member of the I-set of IgSF domains; This group contains the immunoglobulin domain of human Synaptic Adhesion-Like Molecule 5 (SALM5) and similar proteins. The SALM (for synaptic adhesion-like molecules; also known as Lrfn for leucine-rich repeat and fibronectin type III domain containing) family of adhesion molecules consists of five known members: SALM1/Lrfn2, SALM2/Lrfn1, SALM3/Lrfn4, SALM4/Lrfn3, and SALM5/Lrfn5. SALMs share a similar domain structure, containing leucine-rich repeats (LRRs), an immunoglobulin (Ig) domain, and a fibronectin III (FNIII) domain, followed by a transmembrane domain and a C-terminal PDZ-binding motif. SALM5 is implicated in autism spectrum disorders (ASDs) and schizophrenia, induces presynaptic differentiation in contacting axons. SALM5 interacts with the Ig domains of LAR (Leukocyte common Antigen-Related) family receptor protein tyrosine phosphatases (LAR-RPTPs; LAR, PTPdelta, and PTPsigma). In addition, PTPdelta is implicated in ASDs, ADHD, bipolar disorder, and restless leg syndrome. Studies have shown that LAR-RPTPs are novel and splicing-dependent presynaptic ligands for SALM5, and that they mediate SALM5-dependent presynaptic differentiation. Furthermore, SALM5 maintains AMPA receptor (AMPAR)-mediated excitatory synaptic transmission through mechanisms involving the interaction of SALM5 with LAR-RPTPs. This group belongs to the I-set of immunoglobulin superfamily (IgSF) domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand.

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gi 768005958  96 SGRETVYPNGSLLFQNITLEDAGSYTLRTINAsydSDQATGQLHVH 141
Cdd:cd05764   45 SSRTLVYDNGTLDILITTVKDTGAFTCIASNP---AGEATARVELH 87