title: Actions and expression of RAB-GDP dissociation inhibitor in dispersed chief cells from guinea pig stomach.
abstract: Rab proteins are a family of ras-like proteins that are involved in intracellular membrane trafficking. Rab-GDP dissociation inhibitor prevents dissociation of GDP from Rab proteins and extracts Rab proteins from cell membranes in vitro. In the present study, we examined the effects of recombinant rab-GDI on Rab proteins in gastric chief cells. Rab-GDI extracted GTP-binding proteins, including Rab3 and Rab5, from chief cell membranes in a dose-dependent manner. Maximal concentrations of rab-GDI (> or = 50 micrograms/ml) removed approx. 40% of membrane-associated Rab3. Moreover, preincubation of permeabilized chief cells with rab-GDI resulted in a 35% decrease in GTP gamma S(100 microM)-induced pepsinogen secretion, suggesting that membrane-associated Rab proteins are involved in the final stages of secretion. Immunostaining of chief cell cytosolic and membrane fractions with GDI-specific antisera revealed bands at 56 and 48 kDa, respectively, indicating that chief cells express two isoforms of rab-GDI. In gastric chief cells, regulation of Rab proteins by rab-GDI plays an important role in mediating exocytosis.
authors.affiliation: Gastrointestinal Cell Biology Laboratory, State University of New York-Health Science Center at Brooklyn 11203-2098, USA.
authors.forename: R D
authors.initials: RD
authors.lastname: Raffaniello
authors.forename: J
authors.initials: J
authors.lastname: Lin
authors.forename: J P
authors.initials: JP
authors.lastname: Raufman
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D019204:GTP-Binding Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D020730:Guanine Nucleotide Dissociation Inhibitors; D006168:Guinea Pigs; D007700:Kinetics; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010435:Pepsinogens / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000494:pharmacology; D013347:Subcellular Fractions / Q000378:metabolism; D020692:rab3 GTP-Binding Proteins
chemical_list: C086796:GDP dissociation inhibitor 1; D020730:Guanine Nucleotide Dissociation Inhibitors; D009419:Nerve Tissue Proteins; D010435:Pepsinogens; D011993:Recombinant Fusion Proteins; D019204:GTP-Binding Proteins; D020692:rab3 GTP-Binding Proteins