Characterization of KIAA1427 protein as an atypical synaptotagmin (Syt XIII).
Synaptotagmin (Syt) belongs to a family of type-I membrane proteins and is a protein that consists of a short extracellular N-terminus, a single transmembrane domain, two C2 domains and a short C-terminus. Here, we cloned and characterized a mouse orthologue of human KIAA1427 protein as an atypical Syt (named Syt XIII). Subcellular fractionation and antibody-uptake experiments indicate that Syt XIII is indeed a type-I membrane protein, but, unlike other Syt isoforms, lacks an N-terminal extracellular domain. Syt XIII C2 domains show relatively little similarity to Syt I (less than 35% identity at the amino acid level), and lack key amino acids responsible for Ca2+ binding. Because of these substitutions, the Syt XIII C2 domains did not show Ca2+-dependent phospholipid-binding activity, and Syt XIII is thus classified as a Ca2+ -independent isoform. By contrast, the Syt XIII C-terminal domain is highly homologous with other Syt isoforms and can function as a common receptor for neurexin Ialpha in vitro. Since Syt XIII is expressed in various tissues outside the brain, Syt XIII may be involved in constitutive vesicle transport.
Fukuda
M
M
Laboratory for Developmental Neurobiology, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. mnfukuda@brain.riken.go.jp
Mikoshiba
K
K
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002135:Calcium-Binding Proteins; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009479:Neuropeptides; D010743:Phospholipids / Q000378:metabolism; D010802:Phylogeny; D011108:Polymers / Q000378:metabolism; D011487:Protein Conformation; D012333:RNA, Messenger / Q000032:analysis; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000235:genetics; D016415:Sequence Alignment; D050857:Synaptotagmins
D002135:Calcium-Binding Proteins; D018076:DNA, Complementary; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D010743:Phospholipids; D011108:Polymers; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; C494271:SYT13 protein, human; C494272:Syt13 protein, mouse; C112162:neurexophilin; D050857:Synaptotagmins