CYSTEINE STRINGS, CALCIUM CHANNELS AND SYNAPTIC TRANSMISSION

Multidisciplinary studies have led to the discovery and characterizati on of cysteine string proteins (csps) in both Drosophila and Torpedo. Phenotypic analysis of csp mutants in Drosophila demonstrates a crucia l role for csp in synaptic transmission. Expression studies of Torpedo csp (Tcsp) in Xenopus oocytes suggests that the protein has some role in the function of presynaptic Ca2+ channels. However, biochemical pu rification of Tcsp indicates that is associated with synaptic vesicles rather than with the plasma membrane of presynaptic terminals where C a2+ channels reside. These results suggest a model in which csps serve as a link by which docked synaptic vesicles could modulate the activi ty of presynaptic Ca2+ channels.