Multisite phosphorylation of glycogen synthase from rabbit skeletal muscle. Phosphorylation of site 5 by glycogen synthase kinase-5 (casein kinase-II) is a prerequisite for phosphorylation of sites 3 by glycogen synthase kinase-3.
Glycogen synthase kinase-5 (casein kinase-II) phosphorylates glycogen synthase on a serine termed site 5. This residue is just C-terminal to the 3 serines phosphorylated by glycogen synthase kinase-3, which are critical for the hormonal regulation of glycogen synthase in vivo. Although phosphorylation of site 5 does not affect the catalytic activity, it is demonstrated that this modification is a prerequisite for phosphorylation by glycogen synthase kinase-3. Since site 5 is almost fully phosphorylated in vivo under all conditions, the role of glycogen synthase kinase-5 would appear to be a novel one in forming the recognition site for another protein kinase.
D000818:Animals; D001665:Binding Sites; D047388:Casein Kinases; D004837:Epinephrine / Q000494:pharmacology; D006006:Glycogen Synthase / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism*; D008970:Molecular Weight; D009132:Muscles / Q000201:enzymology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D011817:Rabbits
D007328:Insulin; D007527:Isoenzymes; D006006:Glycogen Synthase; D011494:Protein Kinases; D047388:Casein Kinases; D004837:Epinephrine