SAR1b, also known as CMRD, is involved in transport from the endoplasmic reticulum to the Golgi apparatus. This protein is activated by the guanine nucleotide exchange factor PREB. It is involved in the selection of the protein cargo and the assembly of the COPII coat complex. Recombinant human SAR1B protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.