RABIF, also known as guanine nucleotide exchange factor MSS4, is a guanine-nucleotide-releasing protein that may participate in vesicular transport. This protein stimulates GTP-GDP exchange in Sec4 and Rab and binds to a subset of genetically related Rab proteins. Recombinant human RABIF protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.