Modulation of casein kinase II activity by the polar head group of an insulin-sensitive glycosyl-phosphatidylinositol.
A phospho-oligosaccharide, whose production is stimulated by insulin, modulated the activity of partially purified casein kinase II. Whereas at 2 microM the phospho-oligosaccharide stimulated casein kinase II 1.3-fold, higher concentrations of this molecule were inhibitory. 50% inhibition of the enzyme was obtained at 15 microM phospho-oligosaccharide. This biphasic effect of the phospho-oligosaccharide on casein kinase II activity was observed using as substrate both casein or the specific peptide for casein kinase II, Arg-Arg-Arg-Glu-Glu-Glu-Thr-Glu-Glu-Glu. The effect of the phospho-oligosaccharide on casein kinase II was still observed after gel filtration. Deamination of the phospho-oligosaccharide with nitrous acid abolished both the activation and the inhibition of casein kinase II. The glycophospholipid precursor of the phospho-oligosaccharide did not affect casein kinase II activity. Moreover, modulation of casein kinase II activity was not observed with other compounds structurally related to the phospho-oligosaccharide, when used in the micro-molar range. In conclusion, the present results indicate that the phospho-oligosaccharide that mimics and might mediate some of the actions of insulin modulates casein kinase II activity in vitro.
Alemany
S
S
Departamento de Metabolismo, Nutrición, y Hormonas, Fundación Jiménez Díaz, Madrid, Spain.
Puerta
J
J
Guadaño
A
A
Mato
J M
JM
D000595:Amino Acid Sequence; D000818:Animals; D047388:Casein Kinases; D006017:Glycolipids / Q000494:pharmacology*; D017261:Glycosylphosphatidylinositols; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000494:pharmacology*; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D013379:Substrate Specificity
D006017:Glycolipids; D017261:Glycosylphosphatidylinositols; D007328:Insulin; D009844:Oligosaccharides; D010716:Phosphatidylinositols; D011494:Protein Kinases; D047388:Casein Kinases