Protein Phosphatase 1, Regulatory Subunit 7 (PPP1R7)

Type 1 serine/threonine phosphatases consist of a catalytic subunit and one or more regulatory subunits. The noncatalytic subunits not only determine the activity and substrate specificity of the holoenzyme, but also target the phosphatase to a particular cellular location. S. pombe sds22 is a regulatory polypeptide of protein phosphatase-1 that is required for the completion of mitosis. The predicted 360-amino acid PPP1R7 protein contains 11 leucine-rich repeats, which may participate in protein-protein interactions, and multiple putative phosphorylation sites. The amino acid sequences of PPP1R7 and sds22 are 46% identical. Western blot analysis using antibodies against human PPP1R7 detected a 44-kD protein in both the cytoplasm and nucleus of rat liver cells.