Calcineurin subunit B type 2 (CNBII)

Calcineurin subunit B type 2 is a regulatory component encoded by the PPP3R2 gene in humans. It forms part of **calcineurin**, a heterodimeric Ca²⁺/calmodulin-dependent serine/threonine protein phosphatase composed also of a catalytic A subunit. The B type 2 isoform confers calcium sensitivity on the holoenzyme through its EF-hand domains. Calcineurin plays an essential role in Ca²⁺ signaling pathways—most notably activating nuclear factor NFATc transcription factors during T-cell activation—by dephosphorylating them upon increased intracellular calcium levels. The enzyme is potently inhibited by immunosuppressant drugs such as cyclosporin A and voclosporin when these form complexes with their respective cytoplasmic binding proteins. While most research focuses on overall calcineurin function or its major isoforms/subunits rather than specifically on "subunit B type 2," this variant participates similarly within tissues where it is expressed.

Other names

Calcineurin B-like proteinCalcineurin BIICBLPCNBIIPPP3R1-likePPP3RLProtein phosphatase 2B regulatory subunit 2Protein phosphatase 3 regulatory subunit B beta isoform

Drugs such as cyclosporin and voclosporin inhibit calcineurin by binding to immunophilins (cyclophilin or FKBP), forming a complex that inhibits the catalytic activity of the calcineurin holoenzyme. This blocks dephosphorylation/activation of NFAT transcription factors, suppressing T-cell activation and immune responses.