Protein kinase activity and endogenous phosphorylation in subfractions of rat liver mitochondria.
Rat liver mitochondria were subfractionated into outer membrane, intermembrane and mitoplast (inner membrane and matrix) fractions. Of the recovered protein kinase activity, 80-90% was found in the intermembrane fraction, while the rest was associated with mitoplasts. The intermembrane protein kinase was stimulated by cyclic AMP, while the mitoplast enzyme was stimulated by the nucleotide only after treatment with Triton X-100. Extracted protein kinase resolved into three peaks on DEAE-cellulose chromatography. All three peaks were present both in the intermembrane fraction and in mitoplasts. One peak corresponded to the catalytic subunit of cyclic AMP-dependent protein kinases, one was a cyclic AMP-independent enzyme, and the third was the cyclic AMP-dependent type II enzyme. The endogenous incorporation of phosphate was particularly high in the outer mitochondrial membrane, and occurred also in the mitoplast fraction. The incorporation in mitoplasts was to a double band of Mr 47 500, and in outer membranes to apparently heterogeneous material of comparatively low molecular weight.
D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D007525:Isoelectric Focusing; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D013347:Subcellular Fractions / Q000201:enzymology; D013379:Substrate Specificity
D011494:Protein Kinases