Effect of bivalent cations on rat liver cytosol casein (glycogen synthase) kinases 1 and 2. Influence of the protein substrate.
Rat liver cytosol casein kinases 1 and 2 were stimulated by free Mg2+, but the optimal concentration of cation varied with both the casein kinase and the protein substrate used. Mn2+, but neither Ca2+ nor Zn2+, could efficiently substitute for Mg2+ in forming the bivalent-cation-ATP complex used as substrate, but free Mn2+ was inhibitory. The magnitude of these effects depended on the type of casein kinase and the protein substrate used. These results support the idea that, besides the effects of Mg2+ as a component of the Mg-ATP complex, or through interaction with the protein substrate, free Mg2+ is an allosteric effector of both casein kinases.
D000818:Animals; D047388:Casein Kinases; D002364:Caseins / Q000378:metabolism; D002413:Cations, Divalent / Q000494:pharmacology*; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D006006:Glycogen Synthase / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D010774:Phosvitin / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D013379:Substrate Specificity
D002364:Caseins; D002413:Cations, Divalent; D007527:Isoenzymes; D010774:Phosvitin; D006006:Glycogen Synthase; D011494:Protein Kinases; D047388:Casein Kinases; D008274:Magnesium