Journal Article

Phosphoproteins and Protein Kinase Activities Intrinsic to Inner Membranes of Potato Tuber Mitochondria

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

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 40, issue 12, pages 1271-1279
Published in print January 1999 | ISSN: 0032-0781
Published online January 1999 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/oxfordjournals.pcp.a029515
Phosphoproteins and Protein Kinase Activities Intrinsic to Inner Membranes of Potato Tuber Mitochondria

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Inside-out submitochondrial particles (IO-SMP) were isolated and purified from potato (Solanum tuberosum L. cv.) tubers. When these IO-SMP were incubated with [γ 32P]ATP more then 20 proteins became labelled as a result of phosphorylation. The 32P incorporation was stimulated by the oxidising reagent ferricyanide. Except for a 17 kDa protein which was phosphorylated only in the absence of divalent cations, the protein phosphorylation required Mg2+. The time for half-maximum 32P incorporation was 4 mm for the 22 kDa phospho-F1 δ-subunit and 2 min for the 28 kDa phospho-F0 b-subunit of the proton-ATPase. The Km for ATP for the detected phosphoproteins was between 65 μM and 110 μM. The pH optimum for protein phosphorylation in inner membranes was between pH 6 and 8, and for the F1 δ-subunit and the F0 b-subunit the pH optima were 6.5–8 and pH 8, respectively. A 37 kDa phosphoprotein was phosphorylated on a histidine residue while the remainder of the inner membrane proteins were phosphorylated on serine or threonine residues. Two autophosphorylated putative kinases were identified: one at 16.5 kDa required divalent cations for autophosphorylation, while another at 30 kDa did not. A 110 kDa protein was labelled only with [α-32P] suggesting adenylylation.

Keywords: Autophosphorylation; F0F1-ATPase; Inner membrane; Mitochondria; Potato (Solanum tuberosum L.); tubers; Protein phosphorylation

Journal Article.  0 words. 

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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