scholarly journals Effect of bivalent cations on rat liver cytosol casein (glycogen synthase) kinases 1 and 2. Influence of the protein substrate

1985 ◽  
Vol 230 (1) ◽  
pp. 69-74 ◽  
Author(s):  
M Plana ◽  
M D Guasch ◽  
E Itarte
Keyword(s):  
Rat Liver ◽  
Glycogen Synthase ◽  
Casein Kinase ◽  
Bivalent Cation ◽  
Liver Cytosol ◽  
Protein Substrate ◽  
Allosteric Effector ◽  
Casein Kinases ◽  
Glycogen Synthase Kinases ◽  
Rat Liver Cytosol

Rat liver cytosol casein kinases 1 and 2 were stimulated by free Mg2+, but the optimal concentration of cation varied with both the casein kinase and the protein substrate used. Mn2+, but neither Ca2+ nor Zn2+, could efficiently substitute for Mg2+ in forming the bivalent-cation-ATP complex used as substrate, but free Mn2+ was inhibitory. The magnitude of these effects depended on the type of casein kinase and the protein substrate used. These results support the idea that, besides the effects of Mg2+ as a component of the Mg-ATP complex, or through interaction with the protein substrate, free Mg2+ is an allosteric effector of both casein kinases.

scholarly journals Effect of starvation, diabetes and insulin on the casein kinase 2 from rat liver cytosol

1985 ◽  
Vol 225 (2) ◽  
pp. 321-326 ◽  
Author(s):  
C Martos ◽  
M Plana ◽  
M D Guasch ◽  
E Itarte
Keyword(s):  
Rat Liver ◽  
Glycogen Synthase ◽  
Gradient Centrifugation ◽  
Diabetic Rats ◽  
Casein Kinase ◽  
Casein Kinase 2 ◽  
Partial Purification ◽  
Liver Cytosol ◽  
Casein Kinases ◽  
Rat Liver Cytosol

Starvation, diabetes and insulin did not alter the concentration of casein kinases in rat liver cytosol. However, the Km for casein of casein kinase 2 from diabetic rats was about 2-fold lower than that from control animals. Administration of insulin to control rats did not alter this parameter, but increased the Km for casein of casein kinase 2 in diabetic rats. Starvation did not affect the kinetic constants of casein kinases. The effect of diabetes on casein kinase 2 persisted after partial purification of the enzyme by glycerol-density-gradient centrifugation and affected also its activity on other protein substrates such as phosvitin, high-mobility-group protein 14 and glycogen synthase. The results indicate that rat liver cytosol casein kinase 2 is under physiological control.

scholarly journals Heterogeneity of rat liver cytosol casein kinase 2. Association between the α/α' -subunits of casein kinase 2 and the phosphorylatable protein pp49

1991 ◽  
Vol 277 (3) ◽  
pp. 811-818 ◽  
Author(s):  
E Molina ◽  
M Plana ◽  
E Itarte
Keyword(s):  
Rat Liver ◽  
Casein Kinase ◽  
Casein Kinase 2 ◽  
Beta Subunit ◽  
Kinetic Properties ◽  
Liver Cytosol ◽  
Alpha Subunits ◽  
Beta Casein ◽  
Casein Kinases ◽  
Rat Liver Cytosol

Casein kinase 2 activity could be resolved into three peaks by chromatography on DEAE-Sepharose. The peak eluted at high salt concentrations (casein kinase 2b) showed molecular and kinetic properties typical of the heterotetramer composed of alpha-(or alpha'-) and beta-subunits. In contrast, the peak that was eluted at low salt concentrations (casein kinase 2a) contained no beta-subunit but a phosphorylatable protein of 49 kDa (pp49), in addition to the alpha/alpha'-subunits. The presence of alpha/alpha'/alpha"-subunits in preparations of casein kinases 2a and 2b was confirmed by immunological assays. Casein kinase 2a had low specific activity and a very high apparent Km for beta-casein. The peak eluted at intermediate ionic strength contained the alpha/alpha'-subunits and variable amounts of beta-subunit and pp49, and had kinetic properties intermediate between those of casein kinases 2a and 2b. Experiments based on heat inactivation, inhibition by low concentrations of heparin and ability to use GTP as substrate suggested that phosphorylation of pp49 was catalysed by the alpha/alpha'-subunits of casein kinase 2. No similarities were observed in the phosphopeptide maps of pp49 and beta-subunit. These results show that the alpha/alpha'-subunits of rat liver cytosol casein kinase 2 can form complexes not only with the beta-subunit but also with pp49, and that the complexes containing pp49 have a reduced affinity for the exogenous protein substrate beta-casein.

Purification and characterization of two cyclic AMP-independent casein/glycogen synthase kinases from rat liver cytosol

1981 ◽  
Vol 658 (2) ◽  
pp. 334-347 ◽  
Author(s):  
Emilio Itarte ◽  
M. Angels Mor ◽  
Agustí Salavert ◽  
J. Manuel Pena ◽  
JoséFernando Bertomeu ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Rat Liver ◽  
Glycogen Synthase ◽  
Purification And Characterization ◽  
Liver Cytosol ◽  
Glycogen Synthase Kinases ◽  
Rat Liver Cytosol

scholarly journals Inhibition of rat liver cytosol casein kinases by heparin

FEBS Letters ◽  
1982 ◽  
Vol 141 (2) ◽  
pp. 257-262 ◽  
Author(s):  
F. Meggio ◽  
A. Donella Deana ◽  
A.M. Brunati ◽  
L.A. Pinna
Keyword(s):  
Rat Liver ◽  
Liver Cytosol ◽  
Casein Kinases ◽  
Rat Liver Cytosol

Modulators of rat liver cytosol casein kinases 1 and 2

1982 ◽  
Vol 109 (4) ◽  
pp. 1284-1290 ◽  
Author(s):  
M. Plana ◽  
M.D. Guasch ◽  
E. Itarte
Keyword(s):  
Rat Liver ◽  
Liver Cytosol ◽  
Casein Kinases ◽  
Rat Liver Cytosol
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