PPIases accelerate the folding of proteins. It catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides (By similarity). Mediates rapamycin inactivation of TOR protein kinase activity. [protein]-peptidylproline (omega=180) = [protein]-peptidylproline (omega=0) Interacts with FIP37 and with the immunosuppressive drug FK506. Its interaction with FIP37 is inhibited by FK506. Interacts with TOR in a rapamycin-dependent manner. Belongs to the FKBP-type PPIase family.