The cysteine residue in the carboxyl-terminal domain of the m2 muscarinic acetylcholine receptor is not required for receptor-mediated inhibition of adenylate cyclase.
Muscarinic acetylcholine receptors (mAChRs) share with many other receptors of the guanine nucleotide-binding protein-coupled receptor family a highly conserved cysteine residue in the putative cytoplasmic carboxyl-terminal region of the protein. Because elimination of this cysteine in the beta 2-adrenergic receptor has been reported to decrease functional responsiveness, we determined if this cysteine residue is essential for mAChR-effector coupling by replacing Cys457 of the m2 mAChR with glycine and expressing wild-type and mutant receptor in Chinese hamster ovary (CHO) cells. The mutant and wild-type receptors exhibited similar affinities for binding of muscarinic ligands. In addition, the mutation did not affect cell surface localization or receptor-mediated inhibition of adenylate cyclase. These results indicate that the cysteine residue in the carboxyl-terminal domain of the m2 mAChR is not required for ligand binding or mAChR-mediated inhibition of adenylate cyclase in CHO cells.
van Koppen
C J
CJ
Department of Pharmacology, University of Washington, Seattle 98195.
Nathanson
N M
NM
D000067956:Adenylyl Cyclase Inhibitors; D000818:Animals; D001667:Binding, Competitive; D002217:Carbachol / Q000378:metabolism; D002460:Cell Line; D000242:Cyclic AMP / Q000037:antagonists & inhibitors; D003545:Cysteine / Q000737:chemistry*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D018727:Muscarinic Antagonists; D011813:Quinuclidinyl Benzilate / Q000378:metabolism / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000737:chemistry* / Q000502:physiology; D013347:Subcellular Fractions / Q000378:metabolism; D014018:Tissue Distribution
D000067956:Adenylyl Cyclase Inhibitors; D018727:Muscarinic Antagonists; D011976:Receptors, Muscarinic; D006165:Guanylyl Imidodiphosphate; D011813:Quinuclidinyl Benzilate; D002217:Carbachol; D000242:Cyclic AMP; D003545:Cysteine