title: Comparison of kinetic properties between MSS4 and Rab3A GRF GDP/GTP exchange proteins.
abstract: The kinetic properties of MSS4 are studied in comparison with those of Rab3A GRF. MSS4 stimulates the dissociation of [3H]GDP from the lipid-modified and lipid-unmodified forms of Rab3A to the same extent, although Rab3A GRF is more effective on the lipid-modified form than on the lipid-unmodified form. Both MSS4 and Rab3A GRF are inactive on other Rab/Sec/Ypt family members including at least Rab2, Rab5, and Rab11. Rab GDI inhibits the MSS4 and Rab3A GRF effects on the lipid-modified form of Rab3A, but the doses of Rab GDI necessary for this inhibitory effect on Rab3A GRF are lower than those on MSS4. Moreover, Rab GDI slightly inhibits the Rab3A GRF effect on the lipid-unmodified form of Rab3A, but does not affect the MSS4 effect on the lipid-unmodified form of Rab3A. These results suggest that MSS4 and Rab3A GRF are different GDP/GTP exchange proteins for Rab3A.
authors.affiliation: Department of Biochemistry, Kobe University School of Medicine, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Miyazaki
authors.forename: T
authors.initials: T
authors.lastname: Sasaki
authors.forename: K
authors.initials: K
authors.lastname: Araki
authors.forename: N
authors.initials: N
authors.lastname: Ueno
authors.forename: K
authors.initials: K
authors.lastname: Imazumi
authors.forename: F
authors.initials: F
authors.lastname: Nagano
authors.forename: K
authors.initials: K
authors.lastname: Takahashi
authors.forename: Y
authors.initials: Y
authors.lastname: Takai
mesh_terms: D019204:GTP-Binding Proteins / Q000378:metabolism*; D020730:Guanine Nucleotide Dissociation Inhibitors; D020662:Guanine Nucleotide Exchange Factors; D006150:Guanine Nucleotides / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D011506:Proteins / Q000378:metabolism*; D011994:Recombinant Proteins; D013379:Substrate Specificity; D020692:rab3 GTP-Binding Proteins
chemical_list: C086796:GDP dissociation inhibitor 1; D020730:Guanine Nucleotide Dissociation Inhibitors; D020662:Guanine Nucleotide Exchange Factors; D006150:Guanine Nucleotides; D011506:Proteins; C489794:RABIF protein, human; D011994:Recombinant Proteins; D019204:GTP-Binding Proteins; D020692:rab3 GTP-Binding Proteins