Phosphatase Subfamily PPM1K

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Phosphatase Classification: Fold PPM: Superfamily PPM: Family PPM: Subfamily PPM1K (PP2Cκ, PP2Cm, BDP)

PPM1K is a mitochondrial phosphatase that regulates the membrane permeability transition pore and is part of the BCKDA complex.


The PPM1K subfamily emerged in holozoa. It was lost in ecdysozoa and sponge. PPM1K is most similar to the ER-anchored phosphatase subfamily PPM1L.


The PPM1K subfamily has an N-terminal mitochondria target signal (MTS) and phosphatase domain [1, 2]. The MTS (predicted by MitoProt) and phosphatase domain are conserved throughout the PPM1K subfamily.


PPM1K is localized to mitochondrial matrix [2]. It regulates mitochondrial membrane permeability transition pore (MPTP) opening, but the underlying molecular mechanism(s) is unclear [2]. It also functions as pSer phosphatase of the branched-chain a-keto acid dehydrogenase (BCKD) complex [1]. Its loss in Ecdysozoa parallels the loss of the opposing BCKDK kinase. Human PPM1K is widely expressed in different tissues, most abundant in heart [1, 2] and GTEx database.


  1. Joshi M, Jeoung NH, Popov KM, and Harris RA. Identification of a novel PP2C-type mitochondrial phosphatase. Biochem Biophys Res Commun. 2007 Apr 27;356(1):38-44. DOI:10.1016/j.bbrc.2007.02.108 | PubMed ID:17336929 | HubMed [Joshi07]
  2. Lu G, Ren S, Korge P, Choi J, Dong Y, Weiss J, Koehler C, Chen JN, and Wang Y. A novel mitochondrial matrix serine/threonine protein phosphatase regulates the mitochondria permeability transition pore and is essential for cellular survival and development. Genes Dev. 2007 Apr 1;21(7):784-96. DOI:10.1101/gad.1499107 | PubMed ID:17374715 | HubMed [Lu07]
All Medline abstracts: PubMed | HubMed