Calcineurin, also known as protein phosphatase 2B (PP2B), is a calmodulin-dependent, calcium-activated, serine/threonine protein phosphatase composed of a catalytic subunit (calcineurin A) and a tightly bound regulatory subunit (calcineurin B). When activated by calcium in the presence of the regulatory B subunit and calmodulin, Calcineurin A selectively removes phosphates from serine and threonine residues on target proteins. Although ubiquitously expressed, Calcineurin levels are highest in brain, where the phosphatase plays a role in the formation and retention of memories.
