Solubilization and characterization of guanine nucleotide-sensitive muscarinic agonist binding sites from rat myocardium.
Muscarinic receptors from rat myocardial membranes may be solubilized by digitonin in good yield at low temperatures in the presence of Mg2+. Under these conditions, up to 60% of the soluble receptors show high affinity binding for the potent agonist [3H]-oxotremorine-M (KA = 10(9)M-1), which is inhibited by 5'-guanylylimidodiphosphate. The muscarinic binding site labelled with [3H]-oxotremorine-M has a higher sedimentation coefficient (13.4 s) than sites labelled with a 3H antagonist in the presence of guanylylimidodiphosphate (11.6 s) and probably represents a complex between the ligand binding subunit of the receptor and a guanine nucleotide binding protein.
D000818:Animals; D002850:Chromatography, Gel; D004072:Digitonin; D006150:Guanine Nucleotides / Q000494:pharmacology*; D006165:Guanylyl Imidodiphosphate; D066298:In Vitro Techniques; D008274:Magnesium / Q000378:metabolism; D008566:Membranes / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D010095:Oxotremorine; D051381:Rats; D011976:Receptors, Muscarinic / Q000187:drug effects*; D013997:Time Factors
D006150:Guanine Nucleotides; D011976:Receptors, Muscarinic; D006165:Guanylyl Imidodiphosphate; D010095:Oxotremorine; D008274:Magnesium; D004072:Digitonin