Catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides (PubMed:8694762, PubMed:10574961). Plays a role in protein folding, transport and assembly (PubMed:8694762, PubMed:10574961). [protein]-peptidylproline (omega=180) = [protein]-peptidylproline (omega=0) Exclusively expressed in the single anterior excretory cell. During early larval development, peaking at the second larval stage, and dropping off in later development. Belongs to the cyclophilin-type PPIase family.