Characterization of a protein kinase-substrate complex precipitable with Ca2+ from the cytosol fraction of AH-66 hepatoma cells.
A protein kinase-substrate complex was precipitated by adding Ca2+ to the cytosol fraction of AH-66 ascites hepatoma cells. The amount of the precipitated complex was increased with increasing concentrations of Ca2+ and reached a plateau at about 5 mM Ca2+. In the presence of [gamma-32P]ATP, extensive uptake of radioactive phosphate into this complex occurred. The phosphorylation reaction was little affected by addition of cyclic nucleotides, Ca2+-phospholipid, Ca2+-calmodulin. When the complex after phosphorylation was analyzed by SDS-PAGE, a protein with molecular weight of 33,000 was most heavily phosphorylated. These phenomena were also observed for mouse myeloid leukemia cells (M1 cells). By contrast, the addition of Ca2+ to the cytosol fractions of regenerating rat liver, normal rat liver or brain caused little precipitation of the complex.
D000818:Animals; D001923:Brain Chemistry; D002118:Calcium / Q000378:metabolism*; D002122:Calcium Chloride / Q000494:pharmacology; D003600:Cytosol / Q000032:analysis; D008099:Liver / Q000032:analysis; D008114:Liver Neoplasms, Experimental / Q000032:analysis*; D008115:Liver Regeneration; D008274:Magnesium / Q000494:pharmacology; D015636:Magnesium Chloride; D009391:Nephelometry and Turbidimetry; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats
D010750:Phosphoproteins; D015636:Magnesium Chloride; D011494:Protein Kinases; D008274:Magnesium; D002122:Calcium Chloride; D002118:Calcium