A novel receptor of .alpha.-latrotoxin (.alpha.-LTx) which binds .alpha.-LTx independently of calcium (Ca.sup.2+) presence and is thus a mediator of the calcium-independent stimulation of neurotransmitter release by .alpha.-latrotoxin has been isolated, purified and characterized. Designated CIRL (calcium-independent receptor of .alpha.-latrotoxin), it and its endogenous ligands can be used to modulate and regulate spontaneous calcium-independent neurotransmitter release and produce .alpha.-latrotoxin-like effects on the nerve terminal.