PPIases accelerate the folding of proteins. It catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides (By similarity). [protein]-peptidylproline (omega=180) = [protein]-peptidylproline (omega=0) Expressed in leaves, but not in roots. Not expressed in etiolated leaves. Belongs to the FKBP-type PPIase family.