Phosphorylation of heart phosphofructokinase by Ca2+/calmodulin protein kinase.
Phosphofructokinase (PFK) from sheep heart was shown to be phosphorylated by Ca2+/calmodulin protein kinase (CaM-kinase) as well as by cyclic AMP-dependent protein kinase (PKA). HPLC analysis of phosphorylated PFK indicated that phosphorylation by CaM-kinase occurs at least at two sites that are distinct from those recognized by PKA. Phosphorylation by either CaM-kinase of PKA resulted in an increase in sensitivity to ATP inhibition and a small but consistent decrease in Ki for ATP. Phosphorylation by either protein kinase caused a slight increase in the Km of PFK for fructose-6-P. Protein kinase C failed to phosphorylate PFK. Combinations of PKA, CaM-kinase and protein kinase C did not alter the stoichiometry of phosphorylation and did not change the effect on enzyme activity.
Mahrenholz
A M
AM
Department of Pharmacology, Stanford University School of Medicine, California 94305.
Lan
L
L
Mansour
T E
TE
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002851:Chromatography, High Pressure Liquid; D007700:Kinetics; D009206:Myocardium / Q000201:enzymology*; D010732:Phosphofructokinase-1 / Q000302:isolation & purification / Q000378:metabolism*; D010748:Phosphopeptides / Q000302:isolation & purification; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D012756:Sheep
D010748:Phosphopeptides; D011494:Protein Kinases; D010732:Phosphofructokinase-1; D017871:Calcium-Calmodulin-Dependent Protein Kinases