– PPP3R1 belongs to the calcineurin regulatory subunit family. It is a regulatory subunit of calcineurin. Calcineurin is composed of two subunits: calcineurin A (CnA) and calcineurin B (CnB). Dephosphorylation of the nuclear factor of activated T-cells (NF-AT) by Calcineurin is essential for NF-AT activation, nuclear translocation, and early gene expression in T-cells. PPP3R1 is a Ser/Thr-specific calcium and calmodulin-dependent protein phosphatase which takes a vital part in the T cell activation pathway. PPP3R1 is involved in protein dephosphorylation, NFAT protein import into nucleus (ortholog) and epithelial to mesenchymal transition (ortholog). It participates in calcineurin signaling pathway; mitogen activated protein kinase signaling pathway. PPP3R1 interacts with (+)-pilocarpine, 2,4-dinitrotoluene and ammonium chloride. It contains four EF-hand domains and four functional calcium-binding sites. PPP3R1 plays an important role in the T cell activation pathway.