Calcineurin is a calcium/calmodulin-dependent serine/threonine protein phosphatase. The active enzyme is a heterodimer consisting of a catalytic A subunit of 61 kDa and a myristylated regulatory B subunit of 19 kDa that binds calcium. The catalytic A subunit consists of an amino terminal catalytic domain, followed by calmodulin and B subunit binding sites, and a caboxyl-terminal autoinhibitory domain. Calnineurin is the target of immunosuppressant dr
