Regulation of exocytosis in chromaffin cells by phosducin-like protein, a protein interacting with G protein beta gamma subunits

Phosducin and related proteins have been identified as ubiquitous regulator s of signalling mediated by beta gamma subunits of trimeric G proteins. To explore a role for phosducin in regulated exocytosis, me have examined the distribution and putative function of phosducin-like protein (PhLP) in adre nal medullary chromaffin cells. The full-length cDNA encoding the short spl ice variant of PhLP (PhLPs) mas cloned from cultured chromaffin cells, Nati ve PhLPs was found associated with plasma membranes and detected in the sub plasmalemmal area of resting chromaffin cells by confocal immunofluorescenc e analysis. Stimulation with secretagogues triggered a massive redistributi on of PhLPs into the cytoplasm, When microinjected into individual chromaff in cells, recombinant PhLPs inhibited catecholamine secretion evoked by a d epolarizing concentration of K+ without affecting calcium mobilization, Thu s, PhLPs may participate directly in the regulation of calcium-evoked exocy tosis, (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V, All rights reserved.