Abstract
The α subunit of the heterotrimeric Gs protein that couples the β-adrenergic receptor to adenylyl cyclase undergoes post-translational palmitoylation. We examined the dynamics of this modification of αs by metabolic labeling of COS and S49 lymphoma cells under different conditions. The endogenous αs proteins were immunoprecipitated with a peptide-specific antibody, separated by SDS-polyacrylamide gel electrophoresis, and analyzed by fluorography and densitometry. A pulse-chase study of COS cells incubated with [3H]palmitate or [35S]methionine showed that for αs the palmitate turnover (t1/2 ≈ 50 min) was significantly faster than the protein degradation. Treatment of cells with 10 μM isoproterenol, a β-adrenergic receptor agonist, in the presence of [3H]palmitate led to a rapid 4-10-fold increase in the palmitoylation of αs. This increase in palmitoylation was concentration-dependent (EC50 = 0.9 μM) and blocked by the antagonist propranolol. The mutant αs proteins in the unc and H21a S49 cell lines did not show an increase in [3H]palmitate incorporation with isoproterenol treatment. Cholera toxin treatment of COS cells increased the [3H]palmitate incorporation into the αs subunits. These data indicate that palmitoylation of the αs subunit is dynamic and regulated by activation of the αs subunit.
Original language | English (US) |
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Pages (from-to) | 23769-23772 |
Number of pages | 4 |
Journal | Journal of Biological Chemistry |
Volume | 268 |
Issue number | 32 |
State | Published - Nov 15 1993 |
Externally published | Yes |
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology