A CALCIUM and CALMODULIN-dependent serine/threonine protein phosphatase that is composed of the calcineurin A catalytic subunit and the calcineurin B regulatory subunit. Calcineurin has been shown to dephosphorylate a number of phosphoproteins including HISTONES; MYOSIN LIGHT CHAIN; and the regulatory subunits of CAMP-DEPENDENT PROTEIN KINASES. It is involved in the regulation of signal transduction and is the target of an important class of immunophilin-immunosuppressive drug complexes.

NonEC; calcium-calmodulin dependent protein phosphatase found in nerve cells and involved in intracellular signal transduction between the calcium and protein phosphorylation pathways.

Ubiquitous heterodimeric human Calcineurin is Ca(2+)/calmodulin-regulated protein phosphatase involved in many biologic activities as a modifier of phosphorylation status. Composed of widely expressed or tissue-restricted 55-60-kDa calmodulin-binding catalytic subunit (PPP Phosphatase/PP-2B Family) and conserved 19-kD Ca(2+)-sensitive regulatory subunit, Calcineurin appears to regulate glycolytic metabolism, nuclear translocation of NFATC1 transcription factor, sperm motility, and dopaminergic signal transduction and NMDA receptor-dependent synaptic plasticity. (NCI)