THE CALCIUM-INDEPENDENT RECEPTOR OF ALPHA-LATROTOXIN IS NOT A NEUREXIN

alpha-Latrotoxin (alpha-LTx), a vertebrate neurotoxin isolated from Bl ack Widow Spider venom, causes massive spontaneous neurotransmitter re lease. The molecular mechanism(s) by which the toxin exerts its effect is largely unknown. Here we report identification and purification of a novel membrane receptor with high affinity for alpha-LTx. Unlike ne urexin Ia, a previously described high affinity alpha-LTx receptor, th is novel protein binds alpha-LTx independently of Ca2+ presence and th erefore may be a mediator of the calcium-independent stimulation of ne urotransmitter release by alpha-latrotoxin. The major protein componen t of calcium-independent alpha-LTx receptors is a novel Mr 120,000 pro tein which does not belong to the neurexin family. Among several tissu es tested, the Mr 120,000 protein was found only in brain. (C) 1996 Ac ademic Press, Inc.