Protein Phosphatase 1, Regulatory Subunit 2 (PPP1R2)

IPP2 is a protein of 203 residues with a molecular mass of 22.8 kD. The polypeptide shares 92% sequence identity with the rabbit homolog. IPP2 can interact with the catalytic subunit of PP1 to form a heterodimer called PP1I. This complex has been identified in the cytosol of many mammalian tissues. Permana and Mott (1997) cited reports indicating that the isolated heterodimer is inactive but can be activated in vitro by the reversible phosphorylation of IPP2 by glycogen-synthase-kinase at threonine-72. IPP2 can also be phosphorylated on ser86, ser120, and ser121 in vivo, as well as by casein kinase II in vitro.IPP1 is a protein of 165 residues with a molecular mass of 18.6 kD. IPP1 is active only after phosphorylation on a threonine residue by cAMP-dependent protein kinase, while IPP2 does not require phosphorylation.