Leucine rich repeat C-terminal motif; This entry represents the Leucine Rich Repeat C-terminal (LRRCT) capping motif from TRK receptors.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 1772790809 163 NCSCDIRWMQLWQEQGEAKLNSQNLYCINaDGSQLPLFRMNISQCD 208
Cdd:pfam16920   1 RCSCDIRWLQLWQEEGLAGLGTQQLYCLN-DGSKIPLQSMNIPNCG 45

Leucine rich repeat;

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 1772790809 103 TGLQKLTIKNSGLRSIQPRAFAKNPHLRYINLSSNRLTTLSWQLFQTL-SLRELQLEQN 160
Cdd:pfam13855   1 PNLRSLDLSNNRLTSLDDGAFKGLSNLKVLDLSNNLLTTLSPGAFSGLpSLRYLDLSGN 59

Leucine rich repeat C-terminal motif; This entry represents the Leucine Rich Repeat C-terminal (LRRCT) capping motif from TRK receptors.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 1772790809 163 NCSCDIRWMQLWQEQGEAKLNSQNLYCINaDGSQLPLFRMNISQCD 208
Cdd:pfam16920   1 RCSCDIRWLQLWQEEGLAGLGTQQLYCLN-DGSKIPLQSMNIPNCG 45

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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809  218 NLTVREGDNAVITCNGSGSPLPDVDWIVTGLQSInTHQTNLNWTNVHAI-NLTLVNVTSEDNGfTLTCIAENVVGMSNAS 296
Cdd:smart00410   3 SVTVKEGESVTLSCEASGSPPPEVTWYKQGGKLL-AESGRFSVSRSGSTsTLTISNVTPEDSG-TYTCAATNSSGSASSG 80

                   ....*
gi 1772790809  297 VALTV 301
Cdd:smart00410  81 TTLTV 85

Fourth Ig-like domain from smooth muscle myosin light chain kinase and similar domains ; a member of the I-set of IgSF domains; The members here are composed of the fourth immunoglobulin (Ig)-like domain from smooth muscle myosin light chain kinase (MYLK) and similar domains. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. 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. Unlike the V-set, one of the distinctive features of I-set domains is the lack of a C" strand. The structure of this group shows that the fourth Ig-like domain from myosin light chain kinase lacks this strand and thus belongs to the I-set of the IgSF. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809 210 PEISVSHVNLTVREGDNAVITCNGSGSPLPDVDWIVTG--LQSINTHQTnlnwTNVHAINLTLVNVTSEDNGfTLTCIAE 287
Cdd:cd20976     2 PSFSSVPKDLEAVEGQDFVAQCSARGKPVPRITWIRNAqpLQYAADRST----CEAGVGELHIQDVLPEDHG-TYTCLAK 76

                          90
                  ....*....|....
gi 1772790809 288 NVVGMSNASVALTV 301
Cdd:cd20976    77 NAAGQVSCSAWVTV 90

Immunoglobulin I-set domain;

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 1772790809 325 VRGNPPPTLHWLHNGQPLRESKIIHVEYyqEGEISEgcLLFNKPTHYNNGNYTLIAKNPLGTA 387
Cdd:pfam07679  24 VTGTPDPEVSWFKDGQPLRSSDRFKVTY--EGGTYT--LTISNVQPDDSGKYTCVATNSAGEA 82

Leucine rich repeat N-terminal domain; Leucine Rich Repeats pfam00560 are short sequence motifs present in a number of proteins with diverse functions and cellular locations. Leucine Rich Repeats are often flanked by cysteine rich domains. This domain is often found at the N-terminus of tandem leucine rich repeats.

                          10        20
                  ....*....|....*....|.
gi 1772790809  31 ACPANCVCSKTEINCRRPDDG 51
Cdd:pfam01462   1 ACPVPCHCSATVVNCSDRGLT 21

Leucine rich repeat N-terminal domain;

                           10        20
                   ....*....|....*....|....*.
gi 1772790809   31 ACPANCVCSKTEINCRRPDDGnLFPL 56
Cdd:smart00013   1 ACPAPCNCSGTAVDCSGRGLT-EVPL 25

Fifth domain (immunoglobulin-like) of Trk receptor TrkB; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the fifth domain of Trk receptor, TrkB, an immunoglobulin (Ig)-like domain which binds to neurotrophin. The Trk family of receptors are tyrosine kinase receptors, which mediate the trophic effects of the neurotrophin Nerve Growth Factor (NGF) family. Trks are activated by dimerization, leading to autophosphorylation of intracellular tyrosine residues, and triggering the signal transduction pathway. TrkB shares significant sequence homology and domain organization with TrkA and TrkC. The first three domains are leucine-rich domains while the fourth and fifth domains are Ig-like domains playing a part in ligand binding. TrKB is recognized by brain-derived neurotrophic factor (BDNF) and neurotrophin (NT)-4. In some cell systems NT-3 can activate TrkA and TrkB receptors. TrKB transcripts are found throughout multiple structures of the central and peripheral nervous systems. This group belongs to the I-set of IgSF domains

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809 304 PPRVVSLEEPELRLEHCIEFVVRGNPPPTLHWLHNGQPLRESKIIHVEYYQEGEIS-EGCLLFNKPTHYNNGNYTLIAKN 382
Cdd:cd05855     1 PPTITFLELPTRDHHWCIPFTVKGNPKPTLQWFHEGAILNESEYICTKIHVINNTEyHGCLQLDNPTHLNNGIYTLVAKN 80

                          90
                  ....*....|....
gi 1772790809 383 PLGTANQTINGHFL 396
Cdd:cd05855    81 EYGEDEKNVSAHFM 94

Immunoglobulin domain; Members of the immunoglobulin superfamily are found in hundreds of proteins of different functions. Examples include antibodies, the giant muscle kinase titin and receptor tyrosine kinases. Immunoglobulin-like domains may be involved in protein-protein and protein-ligand interactions.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809 214 VSHVNLTVREGDNAVITCNGS-GSPLPDVDWIVTGLQSINTHQTNLNWTNVHAINLTLVNVTSEDNGfTLTCIAENVVGM 292
Cdd:pfam00047   1 SAPPTVTVLEGDSATLTCSAStGSPGPDVTWSKEGGTLIESLKVKHDNGRTTQSSLLISNVTKEDAG-TYTCVVNNPGGS 79

                  ....*..
gi 1772790809 293 SNASVAL 299
Cdd:pfam00047  80 ATLSTSL 86

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 1772790809 210 PEISVSHVNLTVREGDNAVITCNGSGSPLPDVDWIVTGLQSINTHQTNLNWTNVHAiNLTLVNVTSEDNGfTLTCIAEN 288
Cdd:pfam13927   2 PVITVSPSSVTVREGETVTLTCEATGSPPPTITWYKNGEPISSGSTRSRSLSGSNS-TLTISNVTRSDAG-TYTCVASN 78

Fourth Ig-like domain from smooth muscle myosin light chain kinase and similar domains ; a member of the I-set of IgSF domains; The members here are composed of the fourth immunoglobulin (Ig)-like domain from smooth muscle myosin light chain kinase (MYLK) and similar domains. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. 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. Unlike the V-set, one of the distinctive features of I-set domains is the lack of a C" strand. The structure of this group shows that the fourth Ig-like domain from myosin light chain kinase lacks this strand and thus belongs to the I-set of the IgSF. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809 210 PEISVSHVNLTVREGDNAVITCNGSGSPLPDVDWIVTG--LQSINTHQTnlnwTNVHAINLTLVNVTSEDNGfTLTCIAE 287
Cdd:cd20976     2 PSFSSVPKDLEAVEGQDFVAQCSARGKPVPRITWIRNAqpLQYAADRST----CEAGVGELHIQDVLPEDHG-TYTCLAK 76

                          90
                  ....*....|....
gi 1772790809 288 NVVGMSNASVALTV 301
Cdd:cd20976    77 NAAGQVSCSAWVTV 90

Immunoglobulin I-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809 210 PEISVSHVNLTVREGDNAVITCNGSGSPLPDVDWIVTG--LQSINTHQTnlnwTNVHAIN-LTLVNVTSEDNGfTLTCIA 286
Cdd:pfam07679   1 PKFTQKPKDVEVQEGESARFTCTVTGTPDPEVSWFKDGqpLRSSDRFKV----TYEGGTYtLTISNVQPDDSG-KYTCVA 75

                          90
                  ....*....|....*
gi 1772790809 287 ENVVGMSNASVALTV 301
Cdd:pfam07679  76 TNSAGEAEASAELTV 90

Immunoglobulin (Ig)-like domain of myotilin, palladin, and myopalladin; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin (Ig)-like domain in myotilin, palladin, and myopalladin. Myotilin, palladin, and myopalladin function as scaffolds that regulate actin organization. Myotilin and myopalladin are most abundant in skeletal and cardiac muscle; palladin is ubiquitously expressed in the organs of developing vertebrates and plays a key role in cellular morphogenesis. The three family members each interact with specific molecular partners with all three binding to alpha-actinin; In addition, palladin also binds to vasodilator-stimulated phosphoprotein (VASP) and ezrin, myotilin binds to filamin and actin, and myopalladin also binds to nebulin and cardiac ankyrin repeat protein (CARP). This group belongs to the I-set of 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.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809 219 LTVREGDNAVITCNGSGSPLPDVDWIVTG--LQSINTHQTNLNWTNVHAinLTLVNVTSEDNGFtLTCIAENVVGMSNAS 296
Cdd:cd05744    10 LEVQEGRLCRFDCKVSGLPTPDLFWQLNGkpVRPDSAHKMLVRENGRHS--LIIEPVTKRDAGI-YTCIARNRAGENSFN 86

                  ....*
gi 1772790809 297 VALTV 301
Cdd:cd05744    87 AELVV 91

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
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 1772790809 227 AVITCNGSGSPLPDVDWIVTGLQSINTHQTNLNWTNVHAiNLTLVNVTSEDNGfTLTCIAENVVGMSNASVA 298
Cdd:cd00096     1 VTLTCSASGNPPPTITWYKNGKPLPPSSRDSRRSELGNG-TLTISNVTLEDSG-TYTCVASNSAGGSASASV 70

agrin-responsive first immunoglobulin-like domains (Ig1) of the MuSK ectodomain; a member of the I-set of IgSF domains; The members here are composed of the first immunoglobulin-like domains (Ig1) of the Muscle-specific kinase (MuSK). MuSK is a receptor tyrosine kinase specifically expressed in skeletal muscle, where it plays a central role in the formation and maintenance of the neuromuscular junction (NMJ). MuSK is activated by agrin, a neuron-derived heparan sulfate proteoglycan. The activation of MUSK in myotubes regulates the formation of NMJs through the regulation of different processes including the specific expression of genes in subsynaptic nuclei, the reorganization of the actin cytoskeleton and the clustering of the acetylcholine receptors (AChR) in the postsynaptic membrane. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. 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. Unlike the V-set, one of the distinctive features of I-set domains is the lack of a C" strand. The structure of the MuSK lacks this strand and thus it belongs to the I-set of the IgSF. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1772790809 218 NLTVREGDNAVITCNGSGSPLPDVDWIVTG--LQSINT-HQTNLNWTnvhaiNLTLVNVTSEDNGFTLtCIAENVVG 291
Cdd:cd20970    11 TVTAREGENATFMCRAEGSPEPEISWTRNGnlIIEFNTrYIVRENGT-----TLTIRNIRRSDMGIYL-CIASNGVP 81

immunoglobulin-like domain of telokin and similar proteins; a member of the I-set of IgSF domains; The members here are composed of the immunoglobulin (Ig) domain in telokin, the C-terminal domain of myosin light chain kinase which is identical to telokin, and similar proteins. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. 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. Unlike the V-set, one of the distinctive features of I-set domains is the lack of a C" strand. The structure of the telokin Ig domain lacks this strand and thus it belongs to the I-set of the IgSF. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1772790809 325 VRGNPPPTLHWLHNGQPLRESKIIHVEYYQEGEISegcLLFNKPTHYNNGNYTLIAKNPLGTANQT 390
Cdd:cd20973    21 VEGYPDPEVKWMKDDNPIVESRRFQIDQDEDGLCS---LIISDVCGDDSGKYTCKAVNSLGEATCS 83

Third immunoglobulin (Ig)-like domain of Neural Cell Adhesion Molecule 1 (NCAM-1); member of the I-set of IgSF domains; The members here are composed of the third immunoglobulin (Ig)-like domain of Neural Cell Adhesion Molecule (NCAM-1). NCAM plays important roles in the development and regeneration of the central nervous system, in synaptogenesis and neural migration. NCAM mediates cell-cell and cell-substratum recognition and adhesion via homophilic (NCAM-NCAM), and heterophilic (NCAM-non-NCAM), interactions. NCAM is expressed as three major isoforms having different intracellular extensions. The extracellular portion of NCAM has five N-terminal Ig-like domains and two fibronectin type III domains. The double zipper adhesion complex model for NCAM homophilic binding involves Ig1, Ig2, and Ig3. By this model, Ig1 and Ig2 mediate dimerization of NCAM molecules situated on the same cell surface (cis interactions), and Ig3 domains mediate interactions between NCAM molecules expressed on the surface of opposing cells (trans interactions) through binding to the Ig1 and Ig2 domains. The adhesive ability of NCAM is modulated by the addition of polysialic acid chains to the fifth Ig-like domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809 215 SHVNLTVREGDNAVITCNGSGSPLPDVDWIVTGlQSINTHQTNLNWtNVHAINLTLVNVTSEDNGfTLTCIAENVVGMSN 294
Cdd:cd05730     9 SEVNATANLGQSVTLACDADGFPEPTMTWTKDG-EPIESGEEKYSF-NEDGSEMTILDVDKLDEA-EYTCIAENKAGEQE 85

                  ....*...
gi 1772790809 295 ASVALTVY 302
Cdd:cd05730    86 AEIHLKVF 93

Fifth Ig-like domain of Roundabout (Robo) homolog 1/2, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the fifth Ig-like domain of Roundabout (Robo) homolog 1/2 and similar domains. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, -2, and -3), and three mammalian Slit homologs (Slit-1,-2, -3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, -2, and -3 are expressed by commissural neurons in the vertebrate spinal cord and Slits 1, -2, -3 are expressed at the ventral midline. Robo-3 is a divergent member of the Robo family which instead of being a positive regulator of slit responsiveness, antagonizes slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit2 has been shown by surface plasmon resonance experiments and mutational analysis to be is the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site. The fifth Ig-like domain of Robo 1 and 2 is a member of the I-set Ig 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. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809 212 ISVSHVNLTVREGDNAVITCNGSGSPLPDVDWIVTGLQ--SINTHQTNLNWTnvhaiNLTLVNVTSEDNGfTLTCIAENV 289
Cdd:cd20952     2 ILQGPQNQTVAVGGTVVLNCQATGEPVPTISWLKDGVPllGKDERITTLENG-----SLQIKGAEKSDTG-EYTCVALNL 75

                          90
                  ....*....|..
gi 1772790809 290 VGMSNASVALTV 301
Cdd:cd20952    76 SGEATWSAVLDV 87

Second immunoglobulin (Ig)-like domain of fibroblast growth factor (FGF) receptor; member of the I-set of IgSF domains; The members here are composed of the second immunoglobulin (Ig)-like domain of fibroblast growth factor (FGF) receptor. FGF receptors bind FGF signaling polypeptides. FGFs participate in multiple processes such as morphogenesis, development, and angiogenesis. FGFs bind to four FGF receptor tyrosine kinases (FGFR1, FGFR2, FGFR3, FGFR4). Receptor diversity is controlled by alternative splicing producing splice variants with different ligand binding characteristics and different expression patterns. FGFRs have an extracellular region comprised of three IG-like domains, a single transmembrane helix, and an intracellular tyrosine kinase domain. Ligand binding and specificity reside in the Ig-like domains 2 and 3, and the linker region that connects these two. FGFR activation and signaling depend on FGF-induced dimerization, a process involving cell surface heparin or heparin sulfate proteoglycans.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 1772790809 325 VRGNPPPTLHWLHNGQPLR-ESKI--IHVEYYQEGEISEGCLLFNKpthynnGNYTLIAKNPLGTANQT 390
Cdd:cd05857    28 AAGNPTPTMRWLKNGKEFKqEHRIggYKVRNQHWSLIMESVVPSDK------GNYTCVVENEYGSINHT 90

Fourth immunoglobulin (Ig)-like domain of hemolin, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the fourth immunoglobulin (Ig)-like domain of hemolin and similar proteins. Hemolin, an insect immunoglobulin superfamily (IgSF) member containing four Ig-like domains, is a lipopolysaccharide-binding immune protein induced during bacterial infection. Hemolin shares significant sequence similarity with the first four Ig-like domains of the transmembrane cell adhesion molecules (CAMs) of the L1 family. 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 fourth Ig-like domain of hemolin is a member of the I-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set domains, members of the I-set have a discontinuous A strand but lack a C" strand. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809 218 NLTVREGDNAVITCNGSGSPLPDVDWIVTGlqsiNTHQTNLNWTNVHAINLTLVNVTSEDNGfTLTCIAENVVGMSNASV 297
Cdd:cd20978    10 NVVVKGGQDVTLPCQVTGVPQPKITWLHNG----KPLQGPMERATVEDGTLTIINVQPEDTG-YYGCVATNEIGDIYTET 84

                  ....
gi 1772790809 298 ALTV 301
Cdd:cd20978    85 LLHV 88

Immunoglobulin (Ig)-like domain of titin and similar proteins; The members here are composed of the immunoglobulin (Ig)-like domain found in titin-like proteins and similar proteins. Titin (also called connectin) is a fibrous sarcomeric protein specifically found in vertebrate striated muscle. Titin is a giant protein; depending on isoform composition, it ranges from 2970 to 3700 kDa, and is of a length that spans half a sarcomere. Titin largely consists of multiple repeats of Ig-like and fibronectin type 3 (FN-III)-like domains. Titin connects the ends of myosin thick filaments to Z disks and extends along the thick filament to the H zone. It appears to function similarly to an elastic band, keeping the myosin filaments centered in the sarcomere during muscle contraction or stretching. Within the sarcomere, titin is also attached to or is associated with myosin binding protein C (MyBP-C). MyBP-C appears to contribute to the generation of passive tension by titin and like titin has repeated Ig-like and FN-III domains. Also included in this group are worm twitchin and insect projectin, thick filament proteins of invertebrate muscle which also have repeated Ig-like and FN-III domains.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 1772790809 319 HCIEFVVRGNPPPTLHWLHNGQPLRESKIIHVEyyqEGEISEgCLLFNKPTHYNNGNYTLIAKNPLGTANQTIN 392
Cdd:cd05748    10 LRLDIPIKGRPTPTVTWSKDGQPLKETGRVQIE---TTASST-SLVIKNAKRSDSGKYTLTLKNSAGEKSATIN 79

C-terminal immunoglobulin-like domain of the myosin-associated giant protein kinase Twitchin, and similar domains; member of the I-set IgSF domains; The members here are composed of the C-terminal immunoglobulin-like domain of the myosin-associated giant protein kinase Twitchin and similar proteins, including Caenorhabditis elegans and Aplysia californica Twitchin, Drosophila melanogaster Projectin, and similar proteins. These are very large muscle proteins containing multiple immunoglobulin (Ig)-like and fibronectin type III (FN3) domains and a single kinase domain near the C-terminus. In humans these proteins are called Titin. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. 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 Ig-like domain of the Twitchin is a member of the I-set 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. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins (titin, telokin, and twitchin), the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809 219 LTVREGDNAVITCNGSGSPLPDVDWIVTGlQSINTHQTNLNWTNVHAINLTLVNVTSEDNGfTLTCIAENVVGMSNASVA 298
Cdd:cd20949     9 TTVKEGQSATILCEVKGEPQPNVTWHFNG-QPISASVADMSKYRILADGLLINKVTQDDTG-EYTCRAYQVNSIASDMQE 86

                  ...
gi 1772790809 299 LTV 301
Cdd:cd20949    87 RTV 89

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809 304 PPRVVSLEEPELRLE------HCIefvVRGNPPPTLHWLHNGQPLRESKIihveYYQEGEISEGCLLFNKPTHYNNGNYT 377
Cdd:pfam13927   1 KPVITVSPSSVTVREgetvtlTCE---ATGSPPPTITWYKNGEPISSGST----RSRSLSGSNSTLTISNVTRSDAGTYT 73

                  ....*
gi 1772790809 378 LIAKN 382
Cdd:pfam13927  74 CVASN 78

Fourth Ig domain of the neural cell adhesion molecule contactin-2, and similar domains; The members here are composed of the fourth Ig domain of the neural cell adhesion molecule contactin-2. Contactins are comprised of six Ig domains followed by four fibronectin type III (FnIII) domains anchored to the membrane by glycosylphosphatidylinositol. Contactin-2 (also called TAG-1, axonin-1) facilitates cell adhesion by homophilic binding between molecules in apposed membranes. The first four Ig domains form the intermolecular binding fragment which arranges as a compact U-shaped module by contacts between Ig domains 1 and 4, and domains 2 and 3. It has been proposed that a linear zipper-like array forms, from contactin-2 molecules alternatively provided by the two apposed membranes.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1772790809 322 EFVVRGNPPPTLHWLHNGQPL-RESKIihveyyqegEISEGCLLFNKPTHYNNGNYTLIAKNPLGT 386
Cdd:cd05728    20 ECKASGNPRPAYRWLKNGQPLaSENRI---------EVEAGDLRITKLSLSDSGMYQCVAENKHGT 76

Fourth immunoglobulin (Ig)-like domain in neogenin, and similar domains; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the fourth immunoglobulin (Ig)-like domain in neogenin and related proteins. Neogenin is a cell surface protein which is expressed in the developing nervous system of vertebrate embryos in the growing nerve cells. It is also expressed in other embryonic tissues, and may play a general role in developmental processes such as cell migration, cell-cell recognition, and tissue growth regulation. Included in this group is the tumor suppressor protein DCC which is deleted in colorectal carcinoma. DCC and neogenin each have four Ig-like domains followed by six fibronectin type III domains, a transmembrane domain, and an intracellular domain. This group belongs to the I-set of 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.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809 217 VNLTVREGDNAVITCNGSGSPLPDVDWIVTGLQSINTHQTNLnwtnVHAINLTLVNVTSEDNGFtLTCIAENVVGMSNAS 296
Cdd:cd05723     5 SNIYAHESMDIVFECEVTGKPTPTVKWVKNGDVVIPSDYFKI----VKEHNLQVLGLVKSDEGF-YQCIAENDVGNAQAS 79

                  ....*
gi 1772790809 297 VALTV 301
Cdd:cd05723    80 AQLII 84

Sixth immunoglobulin (Ig) domain of contactin; The members here are composed of the sixth 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 1772790809 208 DLPEISVSHVNLTVREGDNAVITCNGSGSPLPDVdwivTGLQSINTHQTNLNWTNVH---------AINLTLVNVTSEDN 278
Cdd:cd04970     1 DATRITLAPSNADITVGENATLQCHASHDPTLDL----TFTWSFNGVPIDLEKIEGHyrrrygkdsNGDLEIVNAQLKHA 76

                          90       100
                  ....*....|....*....|....*..
gi 1772790809 279 GfTLTCIAENVVGMSNASVALTVYYPP 305
Cdd:cd04970    77 G-RYTCTAQTVVDSDSASATLVVRGPP 102

Second immunoglobulin (Ig)-like domain in Robo (roundabout) receptors; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the second immunoglobulin (Ig)-like domain in Robo (roundabout) receptors. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of the Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, Robo2, and Robo3), and three mammalian Slit homologs (Slit-1,Slit-2, Slit-3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, Robo2, and Robo3 are expressed by commissural neurons in the vertebrate spinal cord and Slit-1, Slit-2, Slit-3 are expressed at the ventral midline. Robo-3 is a divergent member of the Robo family which instead of being a positive regulator of Slit responsiveness, antagonizes Slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit-2 has been shown by surface plasmon resonance experiments and mutational analysis to be the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site. This group belongs to the I-set of 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.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 1772790809 326 RGNPPPTLHWLHNGQPLRESKiIHVEyyqegEISEGCLLFNKPTHYNNGNYTLIAKNPLGT 386
Cdd:cd05724    23 RGHPEPTVSWRKDGQPLNLDN-ERVR-----IVDDGNLLIAEARKSDEGTYKCVATNMVGE 77

C-terminal immunoglobulin (Ig)-like domain of myomesin and M-protein; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the C-terminal immunoglobulin (Ig)-like domain of myomesin and M-protein (also known as myomesin-2). Myomesin and M-protein are both structural proteins localized to the M-band, a transverse structure in the center of the sarcomere, and are candidates for M-band bridges. Both proteins are modular, consisting mainly of repetitive Ig-like and fibronectin type III (FnIII) domains. Myomesin is expressed in all types of vertebrate striated muscle; M-protein has a muscle-type specific expression pattern. Myomesin is present in both slow and fast fibers; M-protein is present only in fast fibers. It has been suggested that myomesin acts as a molecular spring with alternative splicing as a means of modifying its elasticity.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809 305 PRVVSLEEPELRlehCIEFVVRGNPPPTLHWLHNGQPLRESKIIHVEYYQEGEISegcLLFNKPTHYNNGNYTLIAKNPL 384
Cdd:cd05737     8 PDVVTIMEGKTL---NLTCNVWGDPPPEVSWLKNDQALAFLDHCNLKVEAGRTVY---FTINGVSSEDSGKYGLVVKNKY 81

                  ..
gi 1772790809 385 GT 386
Cdd:cd05737    82 GS 83

Third immunoglobulin (Ig)-like domain of the L1 cell adhesion molecule (CAM), and similar domains; The members here are composed of the third immunoglobulin (Ig)-like domain of the L1 cell adhesion molecule (CAM). L1 belongs to the L1 subfamily of cell adhesion molecules (CAMs) and is comprised of an extracellular region having six Ig-like domains and five fibronectin type III domains, a transmembrane region and an intracellular domain. L1 is primarily expressed in the nervous system and is involved in its development and function. L1 is associated with an X-linked recessive disorder, X-linked hydrocephalus, MASA syndrome, and spastic paraplegia type 1, that involves abnormalities of axonal growth. This group also contains the chicken neuron-glia cell adhesion molecule, Ng-CAM and human neurofascin.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1772790809 218 NLTVREGDNAVITCNGSGSPLPDVDWI-VTG-LQSINTHQTNLNWTnvhainLTLVNVTSEDNGfTLTCIAENVVGMSNA 295
Cdd:cd05731     4 STMVLRGGVLLLECIAEGLPTPDIRWIkLGGeLPKGRTKFENFNKT------LKIENVSEADSG-EYQCTASNTMGSARH 76

                  ....*.
gi 1772790809 296 SVALTV 301
Cdd:cd05731    77 TISVTV 82

Immunoglobulin (Ig)-like domain of myotilin, palladin, and myopalladin; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin (Ig)-like domain in myotilin, palladin, and myopalladin. Myotilin, palladin, and myopalladin function as scaffolds that regulate actin organization. Myotilin and myopalladin are most abundant in skeletal and cardiac muscle; palladin is ubiquitously expressed in the organs of developing vertebrates and plays a key role in cellular morphogenesis. The three family members each interact with specific molecular partners with all three binding to alpha-actinin; In addition, palladin also binds to vasodilator-stimulated phosphoprotein (VASP) and ezrin, myotilin binds to filamin and actin, and myopalladin also binds to nebulin and cardiac ankyrin repeat protein (CARP). This group belongs to the I-set of 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.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 1772790809 325 VRGNPPPTLHWLHNGQPLRESKiIHVEYYQE-GEISegcLLFNKPTHYNNGNYTLIAKNPLGTA 387
Cdd:cd05744    24 VSGLPTPDLFWQLNGKPVRPDS-AHKMLVREnGRHS---LIIEPVTKRDAGIYTCIARNRAGEN 83

Leucine rich repeat;

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 1772790809  78 RNITSIHIENWRslhtLNAVDMELYTGLQKLT---IKNSGLRSIQPRAFAKNPHLRYINLSSNRL 139
Cdd:pfam13855   1 PNLRSLDLSNNR----LTSLDDGAFKGLSNLKvldLSNNLLTTLSPGAFSGLPSLRYLDLSGNRL 61

First immunoglobulin (Ig)-like constant domain in Robo (roundabout) receptors, and similar domains; The members here are composed of the first immunoglobulin (Ig)-like domain in Roundabout (Robo) receptors. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, Robo2, and Robo3), and three mammalian Slit homologs (Slit1, Slit2, Slit3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, Robo2, and Robo3 are expressed by commissural neurons in the vertebrate spinal cord and Slit1, Slit2,and Slit3 are expressed at the ventral midline. Robo3 is a divergent member of the Robo family which instead of being a positive regulator of Slit responsiveness, antagonizes Slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit2 has been shown by surface plasmon resonance experiments and mutational analysis to be is the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1772790809 327 GNPPPTLHWLHNGQPLRESKIIHVEyyQEGEISEGCLLFNKPTH-----YNNGNYTLIAKNPLGTA 387
Cdd:cd07693    26 GRPTPTIQWLKNGQPLETDKDDPRS--HRIVLPSGSLFFLRVVHgrkgrSDEGVYVCVAHNSLGEA 89