A novel binding protein composed of homophilic tetramer exhibits unique properties for the small GTpase Rab5

Kota Saito, Jun Murai, Hiroaki Kajiho, Kenji Kontani, Hiroshi Kurosu, Toshiaki Katada

Research output: Contribution to journalArticlepeer-review

80 Citations (Scopus)

Abstract

The small GTPase Rab family, which cycles between GTP-bound active and GDP-bound inactive states, plays an important role in membrane trafficking. Among them, Rab5 is involved in early endocytic pathway, and several Rab5-binding proteins have been identified as regulators or effectors to coordinate the docking and fusion processes of endocytic vesicles. We describe a novel binding protein exhibiting unique biochemical properties for Rab5. The Rab5-binding protein enhances GDP-GTP exchange reaction on Rab5 but preferentially interacts with its GTP-bound form. Gel filtration and immunoprecipitation analyses indicate that the Rab5-binding protein functions as a tetramer composed of anti-parallel linkage of two parallel dimers. These results suggest that the newly identified protein may function as an upstream activator and/or downstream effector for Rab5 in endocytic pathway. Possible roles of the quaternary structure have been discussed in terms of the Rab5-mediated signaling.

Original languageEnglish
Pages (from-to)3412-3418
Number of pages7
JournalJournal of Biological Chemistry
Volume277
Issue number5
DOIs
Publication statusPublished - 2002 Feb 1
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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