Calcineurin catalytic subunit alpha (Calcineurin A)

Calcineurin catalytic subunit alpha (commonly referred to as calcineurin A) is the catalytic component of calcineurin, a heterodimeric protein phosphatase highly conserved across eukaryotes. Calcineurin is a calcium and calmodulin-dependent serine/threonine phosphatase responsible for the dephosphorylation—and thus activation—of nuclear factor of activated T-cells (NFAT) transcription factors, leading to the expression of immune regulatory genes such as interleukin-2. Calcineurin A is targeted by key immunosuppressive drugs (e.g., cyclosporin A, tacrolimus) that inhibit its activity and are widely used to prevent organ transplant rejection and treat autoimmune diseases. The human enzyme exists in several isoforms (PPP3CA, PPP3CB, PPP3CC), each encoded by separate genes, and requires binding to the regulatory subunit calcineurin B for full activity and regulation by calcium/calmodulin[1][2][3][4].

Other names

Calcineurin ACalcineurin catalytic subunitProtein phosphatase 3 catalytic subunitPP2B-ACNAPPP3CAPPP3CBPPP3CC

Enzyme inhibition (immunosuppressants: cyclosporin A and tacrolimus bind their immunophilins to form complexes that inhibit calcineurin’s phosphatase activity) Blockade of NFAT dephosphorylation and nuclear translocation, suppressing interleukin-2 expression and T-cell activation