Protein phosphorylation/dephosphorylation in the inner membrane of potato tuber mitochondria

André Struglics, Kenneth M. Fredlund, Yuri M. Konstantinov, John F. Allen, Ian M. Møller

Research output: Contribution to journalArticlepeer-review


Inside-out inner mitochondrial membranes free of matrix proteins were isolated from purified potato tuber (Solanum tuberosum L.) mitochondria and incubated with [γ-32P]ATP. Proteins were separated by SDS-PAGE and visualized by autoradiography. Phosphorylation of inner membrane proteins, including ATPase subunits, was strongly inhibited by the phosphoprotein phosphatase inhibitor NaF. We propose that an inner membrane phosphoprotein phosphatase is required for activation of the inner membrane protein kinase. When prelabelled inner membranes were incubated in the absence of [γ- 32P]ATP, there was no phosphoprotein dephosphorylation unless a soluble matrix fraction was added. This dephosphorylation was inhibited by NaF, but not by okadaic acid. We conclude that the mitochondrial matrix contains a phosphoprotein phosphatase that is responsible for dephosphorylation of inner membrane phosphoproteins. (C) 2000 Federation of European Biochemical Societies.

Original languageEnglish
Pages (from-to)213-217
JournalFEBS Letters
Issue number3
Publication statusPublished - 2000 Jun 23

Subject classification (UKÄ)

  • Biochemistry and Molecular Biology

Free keywords

  • (Plant) mitochondrion
  • Inner membrane
  • Matrix
  • Protein kinase
  • Protein kinase phosphatase
  • Protein phosphatase
  • Protein phosphorylation


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