Characterization of two casein kinase activities in the fungus Mucor rouxii.
Two cyclic-nucleotide independent soluble casein kinase activities (CK I and CK II) from the fungus Mucor rouxii have been isolated, characterized and found to fit in the general classification of type 1 (CK I) and 2 (CK II) casein kinases, according to their enzymatic and structural properties. Both enzymes phosphorylate acidic substrates, require Mg2+ and have a chromatographic behaviour on DEAE-Sepharose and phosphocellulose similar to their mammalian counterparts. CK I has a sedimentation coefficient of 3.5 S, uses ATP as a phosphate donor (Km = 40 microM), phosphorylates casein mainly on serine residues, its activity is strongly inhibited by KCl and polyamines. CK II has a sedimentation coefficient of 7.4 S, uses ATP and GTP as phosphate donors (Km ATP = 10 microM; Km GTP = 40 microM), phosphorylates casein in serine and threonine, its activity is stimulated by KCl and by polyamines and is inhibited by heparin (I50 = 0.5 micrograms/ml). Casein kinase activity associated to particulate fraction (40% of total) has been partially characterized and shown to be similar to the soluble CK I activity.
Pardo
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Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina.
Moreno
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D000596:Amino Acids / Q000032:analysis; D047388:Casein Kinases; D002499:Centrifugation, Density Gradient; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D006493:Heparin / Q000494:pharmacology; D007700:Kinetics; D009089:Mucor / Q000201:enzymology*; D010766:Phosphorylation; D011073:Polyamines / Q000494:pharmacology; D011494:Protein Kinases / Q000032:analysis* / Q000302:isolation & purification; D012995:Solubility; D013379:Substrate Specificity
D000596:Amino Acids; D011073:Polyamines; D006493:Heparin; D011494:Protein Kinases; D047388:Casein Kinases