PPIases accelerate the folding of proteins. It catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides. Plays a major role in negative regulation of the heat shock transcription factor (HSF). [protein]-peptidylproline (omega=180) = [protein]-peptidylproline (omega=0) Interacts with RPD3 and CNS1. Present with 3230 molecules/cell in log phase SD medium.