title: Heparin-activated protein kinase from rabbit muscle: relationship to enzymes of the glycogen synthase kinase-3 category.
abstract: A heparin-activated protein kinase has been previously identified in rabbit skeletal muscle extracts (Z. Ahmad et al. (1985) FEBS Lett. 179, 96-100). Further study has indicated that this enzyme phosphorylates rabbit muscle glycogen synthase in the same tryptic peptide(s) as the protein kinase FA/GSK-3 (glycogen synthase kinase-3) and is able to activate the ATP-Mg2+-dependent protein phosphatase. These results indicate similarities in properties between the two protein kinases. Exposure of the heparin-activated enzyme to trypsin resulted in loss of heparin activation, from 3-fold to 1.3-fold. One hypothesis suggested by this result is that the enzyme FA/GSK-3 could be a derivative of the heparin-activated enzyme that has lost heparin sensitivity. The conceptual importance of this hypothesis is that it may provide a clue to the mode of regulation of this important class of protein kinases.
mesh_terms: D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002845:Chromatography / Q000379:methods; D004789:Enzyme Activation / Q000187:drug effects; D038341:Glycogen Synthase Kinases; D006493:Heparin / Q000494:pharmacology*; D006868:Hydrolysis; D009132:Muscles / Q000201:enzymology*; D010449:Peptide Mapping; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D011817:Rabbits
chemical_list: D006493:Heparin; D011494:Protein Kinases; D038341:Glycogen Synthase Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases