Calcineurin is a calcium-binding and calmodulin-binding protein found in all cells from yeast to mammals, and a calcium-dependent, calmodulin-stimulated protein phosphatase. Composed of a catalytic subunit (A) and a regulatory subunit (B) (By similarity). Interacts with sra. This protein has four functional calcium-binding sites. Belongs to the calcineurin regulatory subunit family.