The protein encoded by this gene is a cis-trans peptidyl-prolyl isomerase that may function in immunoregulation and basic cellular processes involving protein folding and trafficking. This gene is located in a chromosomal region that is deleted in Williams-Beuren syndrome. Defects in this gene may cause male infertility. There are multiple pseudogenes for this gene located nearby on chromosome 7. Alternative splicing results in multiple transcript variants.