PPIases accelerate the folding of proteins. Catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides. Involved in pre-mRNA splicing (PubMed:11884590). [protein]-peptidylproline (omega=180) = [protein]-peptidylproline (omega=0) Belongs to the CWC complex (or CEF1-associated complex), a spliceosome subcomplex composed of the U2, U5 and U6 snRNAs and at least BUD13, BUD31, BRR2, CDC40, CEF1, CLF1, CUS1, CWC2, CWC15, CWC21, CWC22, CWC23, CWC24, CWC25, CWC27, ECM2, HSH155, IST3, ISY1, LEA1, MSL1, NTC20, PRP8, PRP9, PRP11, PRP19, PRP21, PRP22, PRP45, PRP46, SLU7, SMB1, SMD1, SMD2, SMD3, SMX2, SMX3, SNT309, SNU114, SPP2, SYF1, SYF2, RSE1 and YJU2. Present with 2360 molecules/cell in log phase SD medium. Belongs to the cyclophilin-type PPIase family. CWC27 subfamily.