Regulation of galpha i palmitoylation by activation of the 5-hydroxytryptamine-1A receptor.
Nearly all alpha subunits of heterotrimeric GTP-binding regulatory proteins (G proteins) are palmitoylated at cysteine residues near the N terminus. A regulated cycle of palmitoylation could provide a mechanism for modulating G protein signaling by affecting protein interactions and localization of the subunit. In the present studies we utilized both [(3)H]palmitate incorporation and pulse-chase techniques to address the dynamics of alpha(i) palmitoylation in Chinese hamster ovary cells. Both techniques demonstrated a dose- and time-dependent change in [(3)H]palmitate labeling of alpha(i) upon activation of stably expressed 5-hydroxytryptamine-1A receptors by the agonist (+/-)-2-dipropylamino-8-hydroxy-1,2,3, 4-tetrahydronaphthalene hydrobromide (DPAT), with an EC(50) of approximately 10 nm. For the incorporation assay, DPAT elicited an approximate doubling in labeling at the earliest time point measured. For the pulse-chase assay, DPAT promoted a significant loss of radiolabel almost equally as fast. These data demonstrate that the exchange of palmitate on alpha(i) is increased upon stimulation of 5-hydroxytryptamine-1A receptors through the combined processes of depalmitoylation and palmitoylation. These results provide the basis for extending the concept of regulated exchange of palmitate beyond G(s) and provide a framework for exploring the specific functional attributes of the palmitoylated and depalmitoylated forms of subunit.
Chen
C A
CA
Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6084, USA.
Manning
D R
DR
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000631:Aminopyridines / Q000494:pharmacology; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism; D006801:Humans; D019308:Palmitic Acid / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D011985:Receptors, Serotonin / Q000378:metabolism*; D044263:Receptors, Serotonin, 5-HT1; D015398:Signal Transduction; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D000631:Aminopyridines; D010879:Piperazines; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D010566:Virulence Factors, Bordetella; C087205:4-(2'-methoxyphenyl)-1-(2'-(N-(2''-pyridinyl)-4-iodobenzamido)ethyl)piperazine; D019308:Palmitic Acid; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D019205:GTP-Binding Protein alpha Subunits, Gs