Properties of structure and interaction of the receptor for omega-conotoxin, a polypeptide active on Ca2+ channels.
Binding properties of omega-conotoxin (GVIA) to avian and mammalian neuronal Ca2+ channels were investigated using a radioiodinated toxin derivative. An exceptionally high affinity of 0.6 to 2 pM was found both from equilibrium and kinetics measurements. Only one class of non-interacting binding sites was detected. In chick brain, dissucinimidyl suberate specifically cross-linked the toxin to 170 kDa component that comprises a 140 kDa peptide disulfide linked to a 30 kDa peptide, very similar to the heavily glycosylated component of the L-type DHP-sensitive Ca2+ channel. A large peptide of 210-220 kDa was labelled using the azidonitrobenzoyloxy derivative of omega-conotoxin as cross-linking reagent but not the 170/140+30 kDa component. The results suggest that the neuronal Ca2+ channel could be composed by the association of two distinct high molecular weight peptides of 220 kDa and 170/140+30 kDa.
D000818:Animals; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002462:Cell Membrane; D002645:Chickens; D003432:Cross-Linking Reagents; D007473:Ion Channels / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism; D008978:Mollusk Venoms / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D013388:Succinimides; D013574:Synaptosomes / Q000378:metabolism; D014018:Tissue Distribution; D020866:omega-Conotoxin GVIA
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D003432:Cross-Linking Reagents; D007473:Ion Channels; D008978:Mollusk Venoms; D017981:Receptors, Neurotransmitter; D013388:Succinimides; C053157:omega-conotoxin receptor; D020866:omega-Conotoxin GVIA; D002118:Calcium; C019358:disuccinimidyl suberate