{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nPPM1K, also known as PP2Cm, is a mitochondrial serine/threonine phosphatase that dephosphorylates the branched‐chain α‐ketoacid dehydrogenase complex (BCKDC), thereby playing an essential role in the catabolism of branched‐chain amino acids (BCAAs). This enzyme is localized in the mitochondria and its activity is crucial for the metabolic processing of BCAAs, a pathway whose dysregulation has been linked to insulin resistance and metabolic disease."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "3"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nStructural and enzymological characterizations of PPM1K have revealed that its phosphatase activity is strictly dependent on divalent metal ions such as Mg²⁺ and Mn²⁺. Detailed studies, including those of the N94K missense mutant, have demonstrated that precise metal coordination within the active site is critical for catalysis; disruption of this coordination alters the enzyme’s conformation and significantly impairs its activity."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "4"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nGenetic variations in the PPM1K gene, most notably the rs1440581 polymorphism, have been associated with elevated circulating BCAA levels as well as altered glucose metabolism. Intervention studies have shown that the metabolic impacts of these variants can be modulated by dietary fat and carbohydrate intake, linking PPM1K function to insulin resistance and type 2 diabetes risk. Furthermore, other single nucleotide polymorphisms in PPM1K have been related to variations in serum BCAA concentrations and cardiovascular disease risk, thus emphasizing the enzyme’s role in broader metabolic homeostasis."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "5", "end_ref": "8"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nOverall, PPM1K functions as a critical metabolic regulator by integrating mitochondrial BCAA catabolism with genetic and nutritional signals. Its finely tuned metal-dependent phosphatase activity ensures proper energy and amino acid metabolism, while genetic alterations may predispose individuals to metabolic disorders, including type 2 diabetes and cardiovascular disease. Ongoing research into the post‐transcriptional regulation and broader physiological impact of PPM1K continues to shed light on its potential as a therapeutic target in metabolic disease.\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Mandar Joshi, Nam Ho Jeoung, Kirill M Popov, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Identification of a novel PP2C-type mitochondrial phosphatase."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Biochem Biophys Res Commun (2007)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.bbrc.2007.02.108"}], "href": "https://doi.org/10.1016/j.bbrc.2007.02.108"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "17336929"}], "href": "https://pubmed.ncbi.nlm.nih.gov/17336929"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "R Max Wynn, Jun Li, Chad A Brautigam, et al. 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"}, {"type": "b", "children": [{"type": "t", "text": "Regulation of PP2Cm expression by miRNA-204/211 and miRNA-22 in mouse and human cells."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Acta Pharmacol Sin (2015)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1038/aps.2015.119"}], "href": "https://doi.org/10.1038/aps.2015.119"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "26592513"}], "href": "https://pubmed.ncbi.nlm.nih.gov/26592513"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "Meisam Rostaminasab Dolatabad, Lu-Lu Guo, Peng Xiao, et al. 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