title: Identification of sds22 as an inhibitory subunit of protein phosphatase-1 in rat liver nuclei.
abstract: sds22 was originally identified in yeast as a regulator of protein phosphatase-1 that is essential for the completion of mitosis. We show here that a structurally related mammalian polypeptide (41.6 kDa) is part of a 260-kDa species of protein phosphatase-1. This holoenzyme, designated PP-1N(sds22), could be immunoprecipitated with sds22 antibodies and was retained by microcystin-Sepharose. PP-1N(sds22) is a latent phosphatase, but its activity could be revealed by the proteolytic destruction of the noncatalytic subunit(s). PP-1N(sds22) accounted for only 5-10% of the total activity of PP-1 in rat liver nuclear extracts. A synthetic 22-mer peptide, corresponding to a leucine-rich repeat of sds22, specifically inhibited the catalytic subunit of PP-1, showing that at least part of the latency stems from the interaction of the sds22 repeat(s) with PP-1C.
authors.affiliation: Faculteit Geneeskunde, Katholieke Universiteit Leuven, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Dinischiotu
authors.forename: M
authors.initials: M
authors.lastname: Beullens
authors.forename: W
authors.initials: W
authors.lastname: Stalmans
authors.forename: M
authors.initials: M
authors.lastname: Bollen
mesh_terms: D000818:Animals; D018797:Cell Cycle Proteins / Q000302:isolation & purification* / Q000378:metabolism*; D002467:Cell Nucleus / Q000201:enzymology*; D006657:Histones / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D046911:Macromolecular Substances; D004676:Myelin Basic Protein / Q000378:metabolism; D009687:Nuclear Proteins; D010749:Phosphoprotein Phosphatases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D010762:Phosphorylase a / Q000378:metabolism; D054645:Protein Phosphatase 1; D051381:Rats; D012568:Schizosaccharomyces; D013379:Substrate Specificity
chemical_list: D018797:Cell Cycle Proteins; D006657:Histones; D046911:Macromolecular Substances; D004676:Myelin Basic Protein; D009687:Nuclear Proteins; C509753:Ppp1r7 protein, rat; D010762:Phosphorylase a; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1