Peptidyl-prolyl cis-trans isomerase A (PPIA)

Peptidyl-prolyl cis-trans isomerase A, also known as cyclophilin A or PPIA, is an enzyme encoded by the PPIA gene on chromosome 7. It catalyzes the cis-trans isomerization of proline imidic peptide bonds in proteins, which facilitates proper protein folding and function. This enzyme plays key roles in regulating intracellular signaling pathways—including those involved in inflammation and apoptosis—and has been implicated in various diseases such as cancer, inflammatory disorders, and viral infections. Cyclophilin A binds to the immunosuppressive drug cyclosporin A; this interaction underlies its clinical relevance for immunosuppression by inhibiting T-cell activation through calcineurin pathway blockade. The protein belongs to the cyclophilin subfamily within the broader peptidyl-prolyl cis/trans isomerases family.

Other names

Cyclophilin ACypARotamase ACyclosporin A-binding proteinPPIase A

Immunosuppression via inhibition of T-cell activation when bound by cyclosporin A; the drug-target complex inhibits calcineurin signaling in lymphocytes