SYNAPTOPHYSIN, A MAJOR SYNAPTIC VESICLE PROTEIN, IS NOT ESSENTIAL FORNEUROTRANSMITTER RELEASE

Synaptophysin (syp I) is a synaptic vesicle membrane protein that cons titutes approximate to 7% of the total vesicle protein. Multiple lines of evidence implicate syp I in a number of nerve terminal functions. To test these, we have disrupted the murine syp I gene, Mutant mice la cking syp I were viable and fertile. No changes in the structure and p rotein composition of the mutant brains were observed except for a dec rease in synaptobrevin/VAMP II. Synaptic transmission was normal with no detectable changes in synaptic plasticity or the probability of rel ease. Our data demonstrate that one of the major synaptic vesicle memb rane proteins is not essential for synaptic transmission, suggesting t hat its function is either redundant or that it has a more subtle func tion not apparent in the assays used.