Kim S E, Shima H, Nakamura K, Kikuchi K
Division of Biochemical Oncology and Immunology, Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan.
Tohoku J Exp Med. 2000 May;191(1):39-45. doi: 10.1620/tjem.191.39.
Protein phosphatase type-1 (PP1), one of the most abundant Ser/Thr protein phosphatases, plays a central role in the regulation of various cell functions. Almost all the PP1 molecules exist as holoenzymes in vivo consisting of a catalytic subunit (PP1C) and a variable regulatory subunit that regulates substrate specificity and/or subcellular localization. In order to clarify fine regulation of PP1, we overexpressed a nuclear inhibitor of PP1 (NIPP-1) in a Flag-tagged form in mammalian cells. The Flag-tagged NIPP-1 was found to be immunoprecipitated with three isoforms of PP1C, namely, PP1alpha, PP1gamma1, and PP1delta with a similar efficiency, suggesting that NIPP-1 makes a complex with the PP1C through the region conserved among the three isoforms. These results suggested that NIPP-1 can be involved in the regulation of various PP1 holoenzymes in vivo.
