Rab3A is a member of the small GTPase superfamily, Rab family. Rab3A is a small, Ras-like GTPase expressed in neuroendocrine cells, in which Rab3A is linked with secretory vesicle membranes and regulates exocytosis. Rab3A protein may have a role in neurotransmitter release by regulating membrane flow in the nerve terminal.