N-type of calcium channels belongs to a family of voltage-dependent calcium channels and occurs predominantly in neuronal tissue. One of the basic characteristics of this channel type is binding of omega-conotoxin GVIA--a potent blocker of the calcium current through this type of channel. We have found that two proteins with Mw 170-175 kD and 45-60 kD possess omega-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 corresponds to the alpha 1-subunit of N-type of voltage-dependent calcium channel.