Requirement for the synaptic protein interaction site for reconstitution of synaptic transmission by P/Q-type calcium channels

Publisher Website
Google Scholar
Abstract
Ca v 2.1 channels, which conduct P/Q-type Ca 2+ currents, were expressed in superior cervical ganglion neurons in cell culture, and neurotransmission initiated by these exogenously expressed Ca 2+ channels was measured. Deletions in the synaptic protein interaction (synprint) site in the intracellular loop between domains II and III of Ca v 2.1 channels reduced their effectiveness in synaptic transmission. Surprisingly, this effect was correlated with loss of presynaptic localization of the exogenously expressed channels. Ca v 1.2 channels, which conduct L-type Ca 2+ currents, are ineffective in supporting synaptic transmission, but substitution of the synprint site from Ca v 2.1 channels in Ca v 1.2 was sufficient to establish synaptic transmission initiated by L-type Ca 2+ currents through the exogenous Ca v 1.2 channels. Substitution of the synprint site from Ca v 2.2 channels, which conduct N-type Ca 2+ currents, was even more effective than Ca v 2.1. Our results show that localization and function of exogenous Ca 2+ channels in nerve terminals of superior cervical ganglion neurons require a functional synprint site and suggest that binding of soluble NSF attachment protein receptor (SNARE) proteins to the synprint site is a necessary permissive event for nerve terminal localization of presynaptic Ca 2+ channels.