Calcineurin A Recombinant Rabbit mAb

Calcineurin A (CnA) is the catalytic subunit of calcineurin (also known as protein phosphatase 2B), with a molecular weight of approximately 58–64 kDa; it forms a heterodimer with the tightly bound calcium-binding regulatory subunit Calcineurin B (CnB) and is the only serine/threonine protein phosphatase positively regulated by both calcium and calmodulin. Structurally, from its N-terminus to its C-terminus, it comprises a catalytic domain (containing an Fe³⁺–Zn²⁺ binuclear metal active center), a CnB-binding domain, a calmodulin-binding domain, a regulatory domain, and an autoinhibitory domain; in the resting state, the autoinhibitory domain masks the active site and keeps the enzyme at low activity, while calcium signaling triggers a conformational change in CnB and, upon calmodulin binding, relieves autoinhibition. In mammals, there are three CnA isoforms encoded by different genes: α (PPP3CA), β (PPP3CB), and γ (PPP3CC), among which α and β are widely expressed, whereas γ is highly expressed in the testis but also shows significant expression during early brain development. Classical substrates of CnA include the NFAT transcription factor family and DARPP-32, and it plays key roles in immune responses, cardiac function, synaptic plasticity, and neurodevelopment; loss-of-function variants in PPP3CA can cause developmental and epileptic encephalopathy, while gain-of-function variants affecting the autoinhibitory domain are associated with ACCIID syndrome.