PPIases accelerate the folding of proteins. It catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides. [protein]-peptidylproline (omega=180) = [protein]-peptidylproline (omega=0) Binds cyclosporin A (CsA). CsA mediates some of its effects via an inhibitory action on PPIase (By similarity). Interacts with A.tumefaciens VirD2. Ubiquitous, with higher levels in roots and flowers. Confined to vascular tissues. Also detected in stigmas, base of siliques and anthers. Down-regulated by salt and cytokinin treatment. Belongs to the cyclophilin-type PPIase family.