PPIases accelerate the folding of proteins. It catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides (By similarity). [protein]-peptidylproline (omega=180) = [protein]-peptidylproline (omega=0) Induced during the meiotic cycle. Belongs to the cyclophilin-type PPIase family. PPIL4 subfamily.