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Protein phosphorylation/dephosphorylation in the inner membrane of potato tuber mitochondria
Author(s) -
Struglics André,
Fredlund Kenneth M.,
Konstantinov Yuri M.,
Allen John F.,
Møller Ian M.
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)01680-x
Subject(s) - dephosphorylation , phosphoprotein , phosphorylation , inner membrane , phosphatase , okadaic acid , inner mitochondrial membrane , biochemistry , mitochondrion , membrane , kinase , microbiology and biotechnology , protein phosphorylation , biology , chemistry , protein kinase a
Inside‐out inner mitochondrial membranes free of matrix proteins were isolated from purified potato tuber ( Solanum tuberosum L.) mitochondria and incubated with [γ‐ 32 P]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‐ 32 P]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.