Purity: > 90 % by SDS - PAGE Format: Liquid. In 20mM Tris-HCl buffer (pH 7.5) containing 1mM DTT.. RAB18 is a member of a family of Ras-related small GTPase that is lipid-anchored to the cytoplasmic side of the cell membrane. It plays a role in apical recycling and endocytosis and is also thought to be involved in protein transport between early endosomes and the plasma membrane. Recombinant human Rab18 protein, fused to T7-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.