title: Characterization of Rab3A, Rab3B and Rab3C: different biochemical properties and intracellular localization in bovine chromaffin cells.
abstract: In this study we examined the biochemical properties and subcellular localization of Rab3A, Rab3B and Rab3C in bovine adrenal chromaffin cells. The Kd for guanosine 5'-[gamma-thio]triphosphate (GTP[S]) of the three Rab3 proteins was 15, 2700 and 204 nM for Rab3A, Rab3B and Rab3C respectively. The intrinsic GTPase activity of the three Rab3 proteins seemed similar and was increased approx. 3-fold by bovine chromaffin cell lysate. Truncation of the C-terminal 31 amino acid residues decreased the binding affinity for GTP[S] of the three Rab3 proteins. When the C-terminus of Rab3C was replaced with that of Rab3A, the binding affinity of Rab3C for GTP[S] was decreased, but the replacement did not affect the affinity of Rab3B for GTP[S]. Immunostaining experiments showed that Rab3A, Rab3B and Rab3C are localized separately within chromaffin cells. Anti-Rab3A and anti-Rab3C antibodies stained vesicle-like structures, whereas anti-Rab3B antibody distinctly stained the plasma membrane. In summary, bovine chromaffin cells express the three Rab3 proteins but the subcellular localization and biochemical properties of the three Rab3 proteins are distinct.
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan, Republic of China.
authors.forename: C G
authors.initials: CG
authors.lastname: Lin
authors.forename: Y C
authors.initials: YC
authors.lastname: Lin
authors.forename: H W
authors.initials: HW
authors.lastname: Liu
authors.forename: L S
authors.initials: LS
authors.lastname: Kao
mesh_terms: D000313:Adrenal Medulla / Q000166:cytology / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D019439:Chromaffin Cells / Q000166:cytology / Q000378:metabolism*; D017931:DNA Primers; D005455:Fluorescent Antibody Technique; D019204:GTP-Binding Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D005910:Glioma; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006822:Hybrid Cells; D007700:Kinetics; D008969:Molecular Sequence Data; D009447:Neuroblastoma; D016133:Polymerase Chain Reaction; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000032:analysis / Q000096:biosynthesis / Q000737:chemistry; D017384:Sequence Deletion; D020692:rab3 GTP-Binding Proteins
chemical_list: D017931:DNA Primers; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019204:GTP-Binding Proteins; D020692:rab3 GTP-Binding Proteins