Cyclophilins possess the activity of peptidyl-prolyl cis-trans isomerase (PPIase) and are involved in cellular protein folding and protein interactions. PPIE contains two RNA binding domains at the N-terminal region and a PPIase domain at the C-terminal region. It was not known what cellular and physiological roles of PPIE. Recombinant human PPIE was expressed in E.coli and purified by conventional chromatography techniques.