The BioGRID | PUBLICATION VIEW

	Biochem. J. Mar (2001); 354:249-57
Characterization of KIAA1427 protein as an atypical synaptotagmin (Syt XIII).
Fukuda M, Mikoshiba K
Laboratory for Developmental Neurobiology, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. mnfukuda@brain.riken.go.jp
Abstract: 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.
[PUBMED: 11171101]