Inositol 1,3,4,5-tetrakisphosphate binding activities of neuronal and non-neuronal synaptotagmins: Identification of conserved amino acid substitutions that abolish inositol 1,3,4,5-tetrakisphosphate binding to synaptotagmins III, V, and X

Keiji Ibata, Mitsunori Fukuda, Katsuhiko Mikoshiba

研究成果: Article査読

44 被引用数 (Scopus)

抄録

Synaptotagmins I and II are essential for Ca2+-regulated exocytosis of synaptic vesicles from neurons, probably serving as Ca2+ sensors. This Ca2+-sensing function is thought to be disrupted by binding of an inositol 1,3,4,5-tetrakisphosphate (IP4) to the C2B domain of synaptotagmin I or II (Fukuda, M., Moreira, J. E., Lewis, F. M. T., Sugimori, M., Niinobe, M., Mikoshiba, K., and Llinas, R. (1995) Proc. Natl. Acad. Sci. U.S. A. 92, 10708-10712). Recently, several synaptotagmin isoforms, expressed outside the nervous system, have been identified in rats and proposed to be involved in constitutive vesicle traffic. To test whether the inositol high polyphosphates also regulate constitutive vesicle traffic by binding to the non-neuronal synaptotagmins, we examined the IP4 binding properties of the recombinant C2 domains of both neuronal (III, V, X, and XI) and non-neurenal (VI-VIII and IX) synaptotagmins. The C2B domains of synaptotagmins VII-IX and XI had strong IP4 binding activity, but the C2B domain of synaptotagmin VI showed very weak IP4 binding activity. In contrast, there was no significant IP4 binding activity of the C2B domains of synaptetagmins III, V, and X or any of the C2A domains. A phylogenetic tree of the C2 domains of 11 isoforms revealed that synaptotagmins III, V, VI, and X (IP4-insensitive or very weak IP4-binding isoforms) belong to the same branch. Based on the sequence comparison between the IP4-sensitive and -insensitive isoforms, we performed site-directed mutagenesis of synaptotagmin III and identified several amine acid substitutions that abolish IP4 binding activity. Our data suggest that the inositol high polyphosphates might also regulate constitutive vesicle traffic via binding to the IP4-sensitive non-neuronal synaptotagmins.

本文言語English
ページ(範囲)12267-12273
ページ数7
ジャーナルJournal of Biological Chemistry
273
20
DOI
出版ステータスPublished - 1998 5月 15

ASJC Scopus subject areas

  • 生化学
  • 分子生物学
  • 細胞生物学

フィンガープリント

「Inositol 1,3,4,5-tetrakisphosphate binding activities of neuronal and non-neuronal synaptotagmins: Identification of conserved amino acid substitutions that abolish inositol 1,3,4,5-tetrakisphosphate binding to synaptotagmins III, V, and X」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

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