Detection of low-affinity alpha-bungarotoxin binding sites in the rat central nervous system.
The curaremimetic neurotoxin, alpha-bungarotoxin, is shown to interact with two classes of binding sites on rat brain crude mitochondrial fraction membranes. Toxin binding sites are characterized by descriptive, preequilibrium dissociation constants of about 5 and 400 nM. There are at least as many low-affinity toxin binding sites as high-affinity sites. The existence of low- and high-affinity sites is confirmed by experiments with native toxin. Low- and high-affinity toxin binding sites are copurified as judged by sedimentation velocity and density gradient analysis, consistent with the presence of low- and high-affinity toxin binding sites on the same subcellular membrane fragments. The results may offer an explanation for the relatively low antagonistic potency of curaremimetic neurotoxins at acetylcholine-sensitive sites in the vertebrate central nervous system.
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002038:Bungarotoxins / Q000378:metabolism*; D007700:Kinetics; D008928:Mitochondria / Q000378:metabolism; D051381:Rats; D011950:Receptors, Cholinergic / Q000378:metabolism*; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor
D002038:Bungarotoxins; C579165:Chrna7 protein, rat; D011950:Receptors, Cholinergic; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor; D000109:Acetylcholine