Rab3A belongs to the small GTPase superfamily, Rab family. It is a small, Ras-like GTPase expressed in neuroendocrine cells, in which it is associated with secretory vesicle membranes and regulates exocytosis. This protein could play a role in neurotransmitter release by regulating membrane flow in the nerve terminal. Recombinant human RAB3A protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.