title: GDP/GTP exchange reaction-stimulating activity of Rabphilin-3A for Rab3A small GTP-binding protein.
abstract: Rabphilin-3A is a putative target protein for Rab3A, a small GTP-binding protein particularly implicated in neurotransmitter release. Rabphilin-3A interacts more preferentially with GTP-Rab3A than with GDP-Rab3A. Moreover, Rabphilin-3A shows a weak activity to stimulate the GTPase activity of Rab3A and a strong activity to inhibit the Rab3A GTPase-activating protein (GAP)-stimulated GTPase activity of Rab3A. Here, we show that Rabphilin-3A has another activity to stimulate the GDP/GTP exchange reaction of Rab3A. Rabphilin-3A may keep Rab3A continuously in the GTP-bound form by converting again GDP-Rab3A, which may be converted from GTP-Rab3A by Rab3A GAP, to GTP-Rab3A, until the function of Rab3A is accomplished.
authors.affiliation: Department of Molecular Biology and Biochemistry, Osaka University Medical School, Suita, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Fujita
authors.forename: T
authors.initials: T
authors.lastname: Sasaki
authors.forename: K
authors.initials: K
authors.lastname: Araki
authors.forename: K
authors.initials: K
authors.lastname: Takahashi
authors.forename: K
authors.initials: K
authors.lastname: Imazumi
authors.forename: M
authors.initials: M
authors.lastname: Kato
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuura
authors.forename: Y
authors.initials: Y
authors.lastname: Takai
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D002460:Cell Line; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D018411:Spodoptera; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins; D020692:rab3 GTP-Binding Proteins; D000097624:Rabphilin-3A
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D019204:GTP-Binding Proteins; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins; D020692:rab3 GTP-Binding Proteins; D000097624:Rabphilin-3A