May catalyze the cis-trans isomerization of proline imidic peptide bonds in oligopeptides thereby assisting the folding of proteins. May also function as a chaperone, playing a role in intracellular transport of proteins. May also have a protein ubiquitin ligase activity acting as an E3 ubiquitin protein ligase or as a ubiquitin-ubiquitin ligase promoting elongation of ubiquitin chains on proteins. [protein]-peptidylproline (omega=180) = [protein]-peptidylproline (omega=0) S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. Expressed in leaves, flower buds and stems. Lower levels of expression in roots. Belongs to the cyclophilin-type PPIase family. PPIL2 subfamily.