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Inhibition of Brain Gz GAP and Other RGS Proteins by Palmitoylation of G Protein α Subunits

Science  07 Nov 1997:
Vol. 278, Issue 5340, pp. 1132-1135
DOI: 10.1126/science.278.5340.1132

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Abstract

Palmitoylation of the α subunit of the guanine nucleotide-binding protein Gz inhibited by more than 90 percent its response to the guanosine triphosphatase (GTPase)–accelerating activity of Gz GAP, a Gz-selective member of the regulators of G-protein signaling (RGS) protein family of GTPase-activating proteins (GAPs). Palmitoylation both decreased the affinity of Gz GAP for the GTP-bound form of Gαz by at least 90 percent and decreased the maximum rate of GTP hydrolysis. Inhibition was reversed by removal of the palmitoyl group by dithiothreitol. Palmitoylation of Gαz also inhibited its response to the GAP activity of Gα-interacting protein (GAIP), another RGS protein, and palmitoylation of Gαi1 inhibited its response to RGS4. The extent of inhibition of Gz GAP, GAIP, RGS4, and RGS10 correlated roughly with their intrinsic GAP activities for the Gα target used in the assay. Reversible palmitoylation is thus a major determinant of Gzdeactivation after its stimulation by receptors, and may be a general mechanism for prolonging or potentiating G-protein signaling.

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