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 194391176  27 KELVGSVGGAVTFPLK-SKVKQVDSIVWTFNTTPLVtIQPEGGT---IIVTQNRNRERVDFPDGGYSLKLSKLKKNDSGI 102
Cdd:cd16842    1 KEVNGILGGSVTFPLNiSDGQEIENITWSFKTSLAV-IAPGEGGapeIIITDKSYKERLNISQNDYSLQISNLTMEDAGS 79

                         90       100
                 ....*....|....*....|...
gi 194391176 103 YYVGIYSSSLQQPSTQEYVLHVY 125
Cdd:cd16842   80 YRARINTKNSRVTITKEFTLHIY 102

N-terminal immunoglobulin (Ig)-like domain of the signaling lymphocyte activation molecule (SLAM) family; The members here are composed of the N-terminal immunoglobulin (Ig)-like domain of the signaling lymphocyte activation molecule (SLAM) family and similar proteins. The SLAM family is a group of immune-cell specific receptors that can regulate both adaptive and innate immune responses. Members of this group include proteins such as CD84, SLAM (CD150), Ly-9 (CD229), NTB-A (ly-108, SLAM6), 19A (CRACC), and SLAMF9. The genes coding for the SLAM family are nested on chromosome 1, in humans at 1q23, and in mice at 1H2. The SLAM family is a subset of the CD2 family, which also includes CD2 and CD58 located on chromosome 1 at 1p13 in humans. In mice, CD2 is located on chromosome 3, and there is no CD58 homolog. The SLAM family proteins are organized as an extracellular domain with either 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.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 194391176  27 KELVGSVGGAVTFPLK-SKVKQVDSIVWTFNTTPLVtIQPEGGT---IIVTQNRNRERVDFPDGGYSLKLSKLKKNDSGI 102
Cdd:cd16842    1 KEVNGILGGSVTFPLNiSDGQEIENITWSFKTSLAV-IAPGEGGapeIIITDKSYKERLNISQNDYSLQISNLTMEDAGS 79

                         90       100
                 ....*....|....*....|...
gi 194391176 103 YYVGIYSSSLQQPSTQEYVLHVY 125
Cdd:cd16842   80 YRARINTKNSRVTITKEFTLHIY 102

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

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 194391176    27 KELVGSVGGAVTFPLKSKVKQVDSIVWTFNTTPLVTIQPeggtiivtqnrnRERVDFPDGGYSLKLSKLKKNDSGIYY 104
Cdd:smart00410   2 PSVTVKEGESVTLSCEASGSPPPEVTWYKQGGKLLAESG------------RFSVSRSGSTSTLTISNVTPEDSGTYT 67

N-terminal immunoglobulin (Ig)-like domain of the signaling lymphocyte activation molecule (SLAM) family; The members here are composed of the N-terminal immunoglobulin (Ig)-like domain of the signaling lymphocyte activation molecule (SLAM) family and similar proteins. The SLAM family is a group of immune-cell specific receptors that can regulate both adaptive and innate immune responses. Members of this group include proteins such as CD84, SLAM (CD150), Ly-9 (CD229), NTB-A (ly-108, SLAM6), 19A (CRACC), and SLAMF9. The genes coding for the SLAM family are nested on chromosome 1, in humans at 1q23, and in mice at 1H2. The SLAM family is a subset of the CD2 family, which also includes CD2 and CD58 located on chromosome 1 at 1p13 in humans. In mice, CD2 is located on chromosome 3, and there is no CD58 homolog. The SLAM family proteins are organized as an extracellular domain with either 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.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 194391176  27 KELVGSVGGAVTFPLK-SKVKQVDSIVWTFNTTPLVtIQPEGGT---IIVTQNRNRERVDFPDGGYSLKLSKLKKNDSGI 102
Cdd:cd16842    1 KEVNGILGGSVTFPLNiSDGQEIENITWSFKTSLAV-IAPGEGGapeIIITDKSYKERLNISQNDYSLQISNLTMEDAGS 79

                         90       100
                 ....*....|....*....|...
gi 194391176 103 YYVGIYSSSLQQPSTQEYVLHVY 125
Cdd:cd16842   80 YRARINTKNSRVTITKEFTLHIY 102

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 194391176   27 KELVGSVGGAVTFP---LKSKVKQVDSIVWTF-----NTTPLVTIQPEGGTIIVTQNRNRERVDFPDGGYSLKLSKLKKN 98
Cdd:pfam07686   4 REVTVALGGSVTLPctySSSMSEASTSVYWYRqppgkGPTFLIAYYSNGSEEGVKKGRFSGRGDPSNGDGSLTIQNLTLS 83

                          90       100
                  ....*....|....*....|....*.
gi 194391176   99 DSGIYYVGIYSSSLQ--QPSTQEYVL 122
Cdd:pfam07686  84 DSGTYTCAVIPSGEGvfGKGTRLTVL 109

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        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 194391176  24 GPVKEL-VGSVGGAVTFPLKSKVKQVDSIVWTFNTTPLVtiqpEGGTIIVTqnrnrervdfPDGgySLKLSKLKKNDSGI 102
Cdd:cd04969    6 NPVKKKiLAAKGGDVIIECKPKASPKPTISWSKGTELLT----NSSRICIL----------PDG--SLKIKNVTKSDEGK 69

                 .
gi 194391176 103 Y 103
Cdd:cd04969   70 Y 70