IDENTIFICATION AND ISOLATION OF OMEGA-CONOTOXIN BINDING-PROTEIN FROM RABBIT BRAIN

N-type of calcium channels belongs to a family of voltage-dependent ca lcium channels and occurs predominantly in neuronal tissue. One of the basic characteristics of this channel type is binding of pi-conotoxin GVIA - a potent blocker of the calcium current through this type of c hannel. We have found that two proteins with Mw 170-175 kD and 45-60 k D possess pi-conotoxin GVIA binding sites, while the only protein with Mw 170-175 kD was able to transport calcium after reconstitution into the phospholipid vesicles. The same results were obtained from human embryonic brain. Our results suggest that protein with Mw 170-175 kD c orresponds to the alpha(1)-subunit of N-type of voltage-dependent calc ium channel.