Actions and Expression of RAB-GDP Dissociation Inhibitor in Dispersed Chief Cells from Guinea Pig Stomach

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 membranesin vitro.In the present study, we examined the effects of recombinant rab...

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Veröffentlicht in:Biochemical and biophysical research communications 1996-08, Vol.225 (1), p.232-237
Hauptverfasser: Raffaniello, Robert D., Lin, Junying, Raufman, Jean-Pierre
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Sprache:eng
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Zusammenfassung: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 membranesin 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 (≥50 μg/ml) removed approx. 40% of membrane-associated Rab3. Moreover, preincubation of permeabilized chief cells with rab-GDI resulted in a 35% decrease in GTPγS(100 μM)-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.
ISSN:0006-291X
1090-2104
DOI:10.1006/bbrc.1996.1159