Effect of phosphorylation by different protein kinases on the behaviour of glycogen synthase as a substrate for hepatic synthase phosphatases.
Glycogen synthase a from skeletal muscle was phosphorylated in vitro and then used as substrate for the two major synthase phosphatases from liver. Synthase phosphorylated by cAMP-dependent protein kinase (1.4-1.7 P/subunit) was preferentially activated by the cytosolic S-component; in contrast, progressive phosphorylation by casein kinase-1 (0.9-6.5 P/subunit) yielded substrates that were always better dephosphorylated and activated by the glycogen-bound G-component. We have previously isolated from dog liver several types of synthase b that differ by their need for the S- and/or G-component for prompt activation. After additional phosphorylation by a mixture of synthase kinases the activation of these enzyme preparations required the presence of both components.
D000818:Animals; D047388:Casein Kinases; D000242:Cyclic AMP / Q000378:metabolism; D004789:Enzyme Activation; D006006:Glycogen Synthase / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D009132:Muscles / Q000201:enzymology; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats
D007527:Isoenzymes; D000242:Cyclic AMP; D006006:Glycogen Synthase; D011494:Protein Kinases; D047388:Casein Kinases; D010749:Phosphoprotein Phosphatases