Calcium-dependent phospholipid binding to the C2A domain of a ubiquitous form of double C2 protein (Doc2β)

Toshio Kojima, Mitsunori Fukuda, Jun Aruga, Katsuhiko Mikoshiba

研究成果: Article査読

44 被引用数 (Scopus)

抄録

Rabphilin 3A and Doc2α are synaptic vesicle-associated proteins, and are thought to function as Ca2+ sensors in neurotransmitter release. If either rabphilin 3A or Doc2α plays a role in membrane trafficking, like the synaptotagmins, then non-neural forms should be present. Here we describe the isolation of a mouse cDNA which encodes a novel Doc2 homologue (Doc2β) that is present in all tissues. The encoded protein, which is highly homologous to human Doc2α (70% identity), is composed of 412 amino acids with a calculated relative molecular mass (M(r)) of 45,837. The sequence identity is especially high in two C2 domains (74% in C2A and 84% in C2B). Northern and Western blot analyses have shown that Doc2β is expressed in all cell lines and tissues tested. Ca2+-dependent phospholipid binding assaying of recombinant fusion proteins revealed that the single C2A domain, but not the C2B domain, of Doc2β binds phosphatidycholine and phosphatidylserine (2.5:1, w/w) liposomes. The binding is Ca2+-dependent, with an EC50 value of approximately 1 μM and a Hill coefficient of approximately 3, which are comparable to those of synaptotagmins, rabphilin 3A and Doc2α. Our results suggest that Doc2β is involved in constitutive membrane trafficking.

本文言語English
ページ(範囲)671-676
ページ数6
ジャーナルJournal of Biochemistry
120
3
DOI
出版ステータスPublished - 1996 1 1
外部発表はい

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology

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