Protein Phosphatase 1, Regulatory Subunit 3C (PPP1R3C)

Several targeting subunits of PP1 have been identified, including PPP1R5, the glycogen-binding subunits PPP1R3 and PPP1R4, and the nuclear inhibitor of PP1 (PPP1R8).Because there was more than one potential initiation codon, the complete open reading frame predicted a protein of 36.4 kD and 317 amino acids, or 35.6 kD and 312 amino acids. The protein contained a motif involved in the binding of PPP1R3 and PPP1R4 to PP1 and a region homologous to a postulated glycogen-binding site in PPP1R3. The amino acid sequence of the PPP1R5 protein showed 42% identity and 51% similarity to rat liver PPP1R4. Whereas rat PPP1R4 appears to be a liver-specific protein, the PPP1R5 protein was identified in cDNA libraries from several adult tissues and cells.