Receptor regulation of G-protein palmitoylation.
Many alpha subunits of heterotrimeric guanine nucleotide-binding regulatory proteins (G proteins) are palmitoylated. Exposure of cells to the beta-adrenergic agonist isoproterenol increased incorporation of [3H]palmitate specifically into alpha s, the alpha subunit that mediates stimulation of adenylyl cyclase. Pulse-chase experiments suggested that isoproterenol increased turnover of alpha s-bound palmitate. Mutagenesis of Cys-3 in alpha s or alpha o (a homologous alpha subunit) prevented palmitoylation of these proteins. Differing results were obtained when mutations of Cys-3 in alpha s or alpha o were expressed in cells and assayed for their distribution between soluble and membrane fractions. Some alpha subunits, including alpha o, are myristoylated at the amino-terminal glycine residue. Mutation of this glycine prevented both myristoylation and palmitoylation of alpha o, indicating that myristoylation precedes palmitoylation of dually acylated alpha subunits. The amino-terminal sequences and fatty acylation properties of dually acylated alpha subunits are strikingly similar to those of some members of the Src family of protein-tyrosine kinases. The amino-terminal sequence Met-Gly-Cys-Xaa-Xaa-Ser/Cys shared by these proteins may represent a motif for cotranslational and posttranslational processing that includes myristoylation of the glycine residue and reversible palmitoylation of the cysteine residue.
Mumby
S M
SM
Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235-9041.
Kleuss
C
C
Gilman
A G
AG
D000215:Acylation; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004252:DNA Mutational Analysis; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology; D008969:Molecular Sequence Data; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism
D010169:Palmitic Acids; D011943:Receptors, Adrenergic, beta; D011994:Recombinant Proteins; D019308:Palmitic Acid; D019204:GTP-Binding Proteins; D007545:Isoproterenol