PP2C-α (D18C10) XP^® Rabbit mAb #3549

The α isoform of protein phosphatase 2C (PP2C-α) is the catalytic subunit of a widely expressed serine/threonine phosphatase involved in regulation of the cell stress response (1,2). Also known as magnesium-dependent protein phosphatase (PPM1A), this monomeric phosphatase is a member of a conserved group of proteins that acts on many different substrates in numerous pathways. PP2C-α inhibits p38 MAPK and SAPK/JNK pathways activated in response to cell stress as seen in both in vivo and in vitro studies. Specifically, PP2C-α removes phosphates from MKK3 and MKK7, reducing activity of both proteins and inhibiting activation of the downstream kinases JNK and p38 MAPK, respectively (3). Another PP2C-α substrate is IKKβ, the critical regulator of NF-κB signaling. Dephosphorylation of IKKβ at Ser177/181 by PPM1A and PPM1B results in inactivation of IKKβ and inhibition of NF-κB signaling (4). PP2C-α is one of the phosphatases responsible for removing phosphate residues from cyclin dependent protein kinases. In a study using HeLa cell extracts, PP2C-α dephospohrylates CDK2 and CDK6, with a preference toward interacting with CDK2 phosphorylated at Thr160, a residue found in the activating T-loop of the kinase. Removal of phosphates from this site is thought to inactivate cyclin-associated kinases (5). PP2C-α induces cell cycle arrest and apoptosis, likely through activation of p53 though other pathways may also contribute to PP2C-α mediated cell death (6). Additional PP2C-α substrates include the Wnt signaling pathway protein axin (7) and CFTR, a chloride channel protein implicated in cystic fibrosis (8).