Synaptotagmin-like Protein 1-3: A Novel Family of C-Terminal-Type Tandem C2 Proteins

Authors: Fukuda M.¹; Mikoshiba K.^{1, 2}

Source: Biochemical and Biophysical Research Communications, Volume 281, Number 5, March 2001 , pp. 1226-1233(8)

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Abstract:

Synaptotagmins (Syt), rabphilin-3A, and Doc2 belong to a family of carboxyl terminal type (C-type) tandem C2 proteins and are thought to be involved in vesicular trafficking. We have cloned and characterized a novel family of C-type tandem C2 proteins, designated Slp1-3 (synaptotagmin-like protein 1-3). The Slp1-3 C2 domains show high homology to granuphilin-a C2 domains, but the amino-terminal domain of Slp1-3 does not contain any known protein motifs or a transmembrane domain. A subcellular fractionation study indicated that Slp1-3 proteins are peripheral membrane proteins. Phospholipid binding experiments indicated that Slp3 is a Ca²⁺-dependent isoform, but Slp1 and Slp2 are Ca²⁺-independent isoforms, because only the Slp3 C2A domain showed Ca²⁺-dependent phospholipid binding activity. The C-terminus of Slp1-3 also bound neurexin I alpha in vitro, in the same manner as Syt family proteins, which may be important for the membrane association of Slp1-3. In addition, Slp family proteins are differentially distributed in different mouse tissues and at different developmental stages. Copyright 2001 Academic Press.

Keywords: C2 domain; granuphilin; Doc2; rabphilin; phospholipid binding

Language: English

Document Type: Research article

Affiliations: 1: Laboratory for Developmental Neurobiology, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan 2: Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo, 108-8639, Japan

Publication date: 2001-03-01