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) Ubiquitous. Not detected in roots. Down-regulated by dark and high CO(2) treatment. S-nytrosylated during the hypersensitive disease resistance response. Belongs to the cyclophilin-type PPIase family. Extended N-terminus.