Rabbit polyclonal antibody to IPP2 (Q116)

Two inhibitors of protein phosphatase 1 (PP1) include the phosphatase inhibitor 1 (IPP~1) and phosphatase inhibitor 2 (IPP~2) . IPP~2, also known as I~2, interacts with the catalytic subunit of PP1 to form the heterodimer PP1I. The PP1I complex is present in the cytosol of cells in a broad range of vertebrate and invertebrate species. Although the heterodimer itself is inactive, a reversible phosphorylation of IPP~2 at Thr 72 by glycogen~synthase~kinase (GSK3) initiates activation of the heterodimer complex in vitro. Phosphorylation of IPP~2 by casein kinase~II at Ser 86, Ser 120, and Ser 121 enhances the rate of phosphorylation by GSK3 at Thr 72 and effectively activates the heterodimer complex. Besides moderating PP1 activity, IPP~2 may play a role as a chaperone for the correct folding of PP1.