Studies on nicotinic acetylcholine receptors in mammalian brain. Preliminary characterization of membrane-bound alpha-bungarotoxin receptors in rat cerebral cortex.
Binding of alpha-bungarotoxin, labeled with 125I, has been studied in crude membrane preparations of rat cerebral cortex. Membrane-bound receptors appear to consist of at least two saturable subsets: one accounts for the binding of about 50 fmol of toxin/mg of protein, the other binds 120 fmol/mg. For the high affinity sites the dissociation constant for interaction of toxin and receptor extrapolated to zero protein concentration is 9.2 X 10(-10) M. Competition with a variety of agonists and antagonists indicates that toxin binding exhibits the pattern expected for nicotinic acetylcholine receptors. Toxin binding is inhibited by low concentrations of Ca2+ ions (50% inhibition at 3 mM) while higher concentrations are required for Mg2+, Na+, K+, and Li+ (50% inhibition at 0.5 M).
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D002038:Bungarotoxins / Q000378:metabolism*; D002413:Cations, Divalent; D002414:Cations, Monovalent; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D007700:Kinetics; D008024:Ligands; D008297:Male; D051381:Rats; D011950:Receptors, Cholinergic / Q000378:metabolism*; D011978:Receptors, Nicotinic / Q000378:metabolism*
D002038:Bungarotoxins; D002413:Cations, Divalent; D002414:Cations, Monovalent; D008024:Ligands; D011950:Receptors, Cholinergic; D011978:Receptors, Nicotinic; D000109:Acetylcholine