PPIases accelerate the folding of proteins. It catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides. Involved in de-etiolation. Reduces the sensitivity to brassinosteroids by decreasing somehow the abundance of the partially dephosphorylated form of BES1. Triggers the activation of bacterial AvrRpt2 protease activity upon infection by P.syringae. Activated AvrRpt2 confers virulence in plant lacking the RPS2 resistance gene. In plants expressing RPS2, the AvrRpt2-mediated degradation of RIN4 activates RPS2, which induces hypersensitive response (HR) and plant resistance. [protein]-peptidylproline (omega=180) = [protein]-peptidylproline (omega=0) Binds cyclosporin A (CsA). CsA mediates some of its effects via an inhibitory action on PPIase. Interacts with P.syringae AvrRpt2 and with A.tumefaciens VirD2, but not with BES1. Ubiquitous. Up-regulated by light, salt and wounding. Down-regulated by cytokinin treatment. Belongs to the cyclophilin-type PPIase family.