Epidermal growth factor stimulates the phosphorylation of pyruvate kinase in freshly isolated rat hepatocytes.
Epidermal growth factor (EGF) has previously been shown to stimulate gluconeogenesis in rat liver by decreasing the activity of pyruvate kinase [(1988) Biochem. J. 255, 361-364]. Here we investigate the mechanism underlying the inactivation of the enzyme. EGF was found to increase the incorporation of phosphate into pyruvate kinase, with maximal phosphorylation achieved only after 10 min in the presence of the growth factor. The increase in phosphorylation was not additive with that caused by cyclic AMP. Phosphoamino acid analysis of pyruvate kinase isolated from cells treated with EGF indicated that EGF increases phosphorylation solely on serine residues. The exact site of EGF-mediated phosphorylation has yet to be identified.
Moule
S K
SK
Department of Biochemistry, School of Medical Sciences, University Walk, Bristol, UK.
McGivan
J D
JD
D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D008099:Liver / Q000166:cytology / Q000201:enzymology*; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011770:Pyruvate Kinase / Q000378:metabolism*; D051381:Rats; D012694:Serine / Q000378:metabolism
D010710:Phosphates; D012694:Serine; D004815:Epidermal Growth Factor; D000242:Cyclic AMP; D011770:Pyruvate Kinase