Reciprocal regulation of P/Q-type Ca2+ channels by SNAP-25, syntaxin and synaptotagmin

Rapid synaptic transmission requires close proximity of docked neurotransmitter-containing synaptic vesicles and voltage-gated Ca2+ channels at presynaptic active zones. Here we show that the plasma membrane SNARE protein SNAP-25 specifically inhibited the activity of P/Q-type Ca2+ channels, and formation of a mature SNARE complex containing syntaxin and synaptotagmin reactivated them. In a nerve terminal, this mechanism would ensure that Ca2+ entry through P/Q-type Ca2+ channels occurs primarily near active zones with docked synaptic vesicles and efficiently evokes neurotransmitter release.