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) Aerial parts. Up-regulated by light. Down-regulated by dark. Both gene predictions and some EST data suggest that there may be an additional exon at the C-terminus, adding another 10 kDa to the protein.