Existence of different populations of the dendrotoxin I binding protein associated with neuronal K+ channels.
The binding sites of dendrotoxin I, mast cell degranulating peptide, and beta-bungarotoxin are thought to be associated with neuronal K+ channels. The different binding sites seem to reside on the same molecular assembly as each toxin can allosterically inhibit the binding of the others. Affinity chromatography on a beta-BTX Aca 22 affinity column has shown that there is an heterogeneous population of dendrotoxin I binding proteins. Two subtypes were separated: DTXI binding proteins with low affinity for beta-BTX (60-70% of total) and DTXI binding proteins with high affinity for beta-BTX (30-40% of total). Binding of 125I-DTXI and 125I-MCD to the former subtype is inhibited by beta-BTX with a low affinity (IC50 = 560 nM), while inhibition at the latter subtype occurs with a high affinity (IC50 = 10-16 nM). The DTXI binding subtype with low affinity for beta-BTX contains most (85-90%) of the binding sites for 125I-MCD.
Rehm
H
H
Centre de Biochimie, Centre National de la Recherche Scientifique, Nice, France.
Lazdunski
M
M
D000818:Animals; D001665:Binding Sites; D002038:Bungarotoxins / Q000378:metabolism; D002846:Chromatography, Affinity; D007473:Ion Channels / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D009498:Neurotoxins / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels; D051381:Rats; D011950:Receptors, Cholinergic / Q000378:metabolism*
D002038:Bungarotoxins; D007473:Ion Channels; D009498:Neurotoxins; D015221:Potassium Channels; D011950:Receptors, Cholinergic; C042467:dendrotoxin receptor; D011188:Potassium