title: Metals in the active site of native protein phosphatase-1.
abstract: Protein phosphatase-1 (PP1) is a major protein Ser/Thr phosphatase in eukaryotic cells. Its activity depends on two metal ions in the catalytic site, which were identified as manganese in the bacterially expressed phosphatase. However, the identity of the metal ions in native PP1 is unknown. In this study, total reflection X-ray fluorescence (TXRF) was used to detect iron and zinc in PP1 that was purified from rabbit skeletal muscle. Metal exchange experiments confirmed that the distinct substrate specificity of recombinant and native PP1 is determined by the nature of their associated metals. We also found that the iron level associated with native PP1 is decreased by incubation with inhibitor-2, consistent with a function of inhibitor-2 as a PP1 chaperone.
authors.affiliation: Laboratory of Biosignaling and Therapeutics, Department of Cellular and Molecular Medicine, KU Leuven, Belgium; Department of Chemistry, KU Leuven, Belgium.
authors.forename: Ewald
authors.initials: E
authors.lastname: Heroes
authors.affiliation: Interuniversity Micro Electronics Center (IMEC), Leuven, Belgium.
authors.forename: Jens
authors.initials: J
authors.lastname: Rip
authors.affiliation: Laboratory of Biosignaling and Therapeutics, Department of Cellular and Molecular Medicine, KU Leuven, Belgium.
authors.forename: Monique
authors.initials: M
authors.lastname: Beullens
authors.affiliation: Department of Chemistry, KU Leuven, Belgium.
authors.forename: Luc
authors.initials: L
authors.lastname: Van Meervelt
authors.affiliation: Department of Chemistry, KU Leuven, Belgium; Interuniversity Micro Electronics Center (IMEC), Leuven, Belgium.
authors.forename: Stefan
authors.initials: S
authors.lastname: De Gendt
authors.affiliation: Laboratory of Biosignaling and Therapeutics, Department of Cellular and Molecular Medicine, KU Leuven, Belgium. Electronic address: Mathieu.Bollen@med.kuleuven.be.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Bollen
mesh_terms: D000818:Animals; D020134:Catalytic Domain; D007501:Iron / Q000737:chemistry*; D018482:Muscle, Skeletal / Q000201:enzymology; D054645:Protein Phosphatase 1 / Q000037:antagonists & inhibitors / Q000737:chemistry*; D011817:Rabbits; D015032:Zinc / Q000737:chemistry*
chemical_list: D007501:Iron; D054645:Protein Phosphatase 1; D015032:Zinc
keywords: Inhibitor-2; Iron; Protein phosphatase-1; TXRF; Zinc