Palmitoylation of muscarinic acetylcholine receptor m2 subtypes: reduction in their ability to activate G proteins by mutation of a putative palmitoylation site, cysteine 457, in the carboxyl-terminal tail.

摘要: Abstract A putative palmitoylation site, Cys457, of muscarinic acetylcholine receptor m2 subtype (m2 receptor) was eliminated by conversion to alanine or stop codon site-directed mutagenesis. The mutant C457A not metabolically labeled with [3H]palmitic acid when expressed in Sf9 cells, whereas the wild-type under same conditions. These results confirm that Cys457 is site. rate markedly accelerated addition agonist, indicating reaction affected conformational changes induced agonist binding. mutants without were purified and reconstituted G proteins into phospholipid vesicles. Both good substrates protein-coupled kinase 2 phosphorylation stimulated protein βγ subunits, as case for receptors. receptors interacted activate Gi2and Go. However, [35S]GTPγS binding Gi2was half much wild type, proportion guanine nucleotide-sensitive high-affinity sites significantly less (42–42%) compared type (62%). indicate an absolute requirement their interaction but enhances ability interact proteins.