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Emergence of reversible phosphorylation in the mitochondria
Author(s) -
Rardin Matthew,
Wiley Sandra E.,
Dixon Jack E.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1049.3
Subject(s) - mitochondrion , intermembrane space , phosphorylation , phosphatase , microbiology and biotechnology , inner membrane , protein tyrosine phosphatase , inner mitochondrial membrane , tyrosine phosphorylation , biology , translocase of the outer membrane , chemistry , biochemistry , bacterial outer membrane , mitochondrial membrane transport protein , escherichia coli , gene
Reversible phosphorylation within mitochondria is a rapidly emerging topic in cell signaling. In order to determine which phosphatases are involved in this process we screened several protein tyrosine phosphatases (PTP) as potential candidates for mitochondrial localization. Of those examined, two of the atypical Dual‐Specificity Phosphatases (DSP) appeared to localize to mitochondria. DSP18 and DSP21 are catalytically active phosphatases. While DSP18 is widely expressed in rat tissues, DSP21 is selectively expressed in testes. We demonstrate that DSP18 and DSP21 are targeted to the mitochondria by unique internal localization signals. Electron microscopy and subfractionation of rat kidney mitochondria revealed endogenous DSP18 as being located within the mitochondria. Subsequent treatment of mitochondrial membranes established that DSP18 is located in the intermembrane space as a peripheral membrane protein of the inner membrane. In contrast, subfractionation of rat testes mitochondria revealed DSP21 is localized to the matrix as a peripheral membrane protein of the inner membrane. This work, which rigorously demonstrates the unique location of two highly similar DSPs on either side of the inner membrane, provides further evidence that reversible phosphorylation is an inherent aspect of mitochondrial function.