Heroes Ewald, Rip Jens, Beullens Monique, Van Meervelt Luc, De Gendt Stefan, Bollen Mathieu
Laboratory of Biosignaling and Therapeutics, Department of Cellular and Molecular Medicine, KU Leuven, Belgium; Department of Chemistry, KU Leuven, Belgium.
Interuniversity Micro Electronics Center (IMEC), Leuven, Belgium.
J Inorg Biochem. 2015 Aug;149:1-5. doi: 10.1016/j.jinorgbio.2015.03.012. Epub 2015 Mar 31.
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.
蛋白磷酸酶-1（PP1）是真核细胞中一种主要的蛋白丝氨酸/苏氨酸磷酸酶。其活性取决于催化位点中的两种金属离子，在细菌表达的磷酸酶中这两种离子被鉴定为锰。然而，天然PP1中金属离子的身份尚不清楚。在本研究中，全反射X射线荧光光谱法（TXRF）被用于检测从兔骨骼肌中纯化得到的PP1中的铁和锌。金属交换实验证实，重组PP1和天然PP1不同的底物特异性是由其相关金属的性质决定的。我们还发现，与天然PP1相关的铁水平会因与抑制剂-2孵育而降低，这与抑制剂-2作为PP1伴侣蛋白的功能一致。
