LOCALIZATION OF RABPHILIN-3A ON THE SYNAPTIC VESICLE

Rabphilin-3A is a putative target protein for Rab3A small GTP-binding protein which is implicated in neurotransmitter release. Rabphilin-3A is expressed mainly in brain, but its subcellular localization remains to be clarified. Immunohistochemical analysis has revealed that Rabph ilin-3A is most abundant in the synaptic area of the rat cerebellum, r etina, and neuromuscular junction. Ultrastructural analysis of the neu romuscular junction using the immunogold method indicates that Rabphil in-3A is localized on the synaptic vesicle. Subcellular fractionation analysis of rat brain has shown that Rabphilin-3A is most highly conce ntrated in the purified synaptic vesicle fraction. These results indic ate that Rabphilin-3A is localized on the synaptic vesicle in the pres ynapse. (C) 1994 Academic Press, Inc.