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GDP/GTP exchange reaction‐stimulating activity of Rabphilin‐3A for Rab 3A small GTP‐binding protein
Author(s) -
Fujita Yasuyuki,
Sasaki Takuya,
Araki Keishi,
Takahashi Kazuo,
Imazumi Katsunori,
Kato Masaki,
Matsuura Yoshiharu,
Takai Yoshimi
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)01015-3
Subject(s) - rab , gtpase , gtp' , microbiology and biotechnology , biochemistry , chemistry , biology , enzyme
Rabphilin‐3A is a putative target protein for Rab 3A, a small GTP‐binding protein particularly implicated in neurotransmitter release. Rabphilin‐3A interacts more preferentially with GTP‐ Rab 3A than with GDP‐ Rab 3A. Moreover, Rabphilin‐3A shows a weak activity to stimulate the GTPase activity of Rab 3A and a strong activity to inhibit the Rab 3A GTPase‐activating protein (GAP)‐stimulated GTPase activity of Rab 3A. Here, we show that Rabphilin‐3A has another activity to stimulate the GDP/GTP exchange reaction of Rab 3A. Rabphifin‐3A may keep Rab 3A continuously in the GTP‐bound form by converting again GDP‐ Rab 3A, which may be converted from GTP‐ Rab 3A by Rab 3A GAP, to GTP‐ Rab 3A, until the function of Rab 3A is accomplished.