PPIases accelerate the folding of proteins. It catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides. Co-chaperone that negatively modulates thermotolerance by interacting with FKBP62 and decreasing the HSFA2-mediated accumulation of chaperones of the small-HSPs family. Plays a positive role in tolerance to intracellular acid stress by maintaining the pH homeostasis. May be a part of transcription regulation pathways upon pathogen infection. [protein]-peptidylproline (omega=180) = [protein]-peptidylproline (omega=0) This PPIase probably binds calmodulin (By similarity). Forms heterodimers with FKBP62/ROF1. Relocalization from the cytoplasm into the nucleus is induced by heat shock. Expressed in the whole plant. By heat shock and by intracellular acid stress. Up-regulated by HSFA2 and upon pathogen infection. Acid sensitivity and increased susceptibility to P.syringae infection. Belongs to the FKBP-type PPIase family.