Identification of a novel PP2C-type mitochondrial phosphatase.
A novel phosphatase has been cloned and partially characterized. It has a mitochondrial leader sequence and its amino acid sequence places it in the PP2C family like two known mitochondrial phosphatases. Western blot analysis of subcellular fractions and confocal microscopy of 3T3L1 preadipocytes expressing the GFP-tagged protein confirm its mitochondrial localization. Western blot analysis indicates that the protein is expressed in several mouse tissues, with highest expression in brain, heart, liver, and kidney. The recombinant protein exhibits Mn(2+)-dependent phosphoserine phosphatase activity against the branched-chain alpha-keto acid dehydrogenase complex, suggesting the enzyme may play a role in regulation of branched chain amino acid catabolism. Whether there are other mitochondrial substrates for the enzyme is not known.
Joshi
Mandar
M
Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202-5122, USA.
Jeoung
Nam Ho
NH
Popov
Kirill M
KM
Harris
Robert A
RA
D041721:3T3-L1 Cells; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007655:Ketoglutarate Dehydrogenase Complex / Q000378:metabolism; D007700:Kinetics; D008345:Manganese / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000201:enzymology* / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009596:Nitrophenols / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000235:genetics* / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D000071636:Protein Phosphatase 2C; D021382:Protein Sorting Signals / Q000235:genetics; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D018076:DNA, Complementary; D024101:Mitochondrial Proteins; D009596:Nitrophenols; D009943:Organophosphorus Compounds; D021382:Protein Sorting Signals; D011768:Pyruvate Dehydrogenase Complex; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; C008644:nitrophenylphosphate; D008345:Manganese; D007655:Ketoglutarate Dehydrogenase Complex; D010749:Phosphoprotein Phosphatases; D000071636:Protein Phosphatase 2C; D010744:Phosphoric Monoester Hydrolases; C022394:phosphoserine phosphatase