Protein phosphokinase

S ATP -I- [DNA-directed eukaryotic RNA polymerase II subunit Ila] (<4> distinct from other protein phosphokinases, transfers about 20 phosphates to the heptapeptide repeats Pro-Thr-Ser-Pro-Ser-Tyr-Ser in C-terminal domain of MW 220000 subunit of RNA-polymerase II [7] <4> substrates are RNA-polymerase II subunits of wheat germ, soy bean, pea and human [7] phosphorylates predominantly Ser-residues [1-3,5,7] <1> kinase CTDKl almost exclusively phosphorylates Ser-residues [5] <1> kinase CTDK2 phosphorylates to a lesser extent Thr-resi-dues [1] <3-5> phosphorylates to a lesser extent Thr-residues [1,5,7] <1> phosphorylates Ser- and Thr-residues equally [6] <1,3,5> phosphorylates not Tyr-residues [1,6] <1> kinase CTDKl 33 mol phosphate per mol IIA-subunit [5] <1> kinase CTDK2 40-50 mol phosphate per mol IIA-subunit, i.e. 1 phosphate per heptapeptide repeat [5] <4> no substrate is GTP [7] <2,4> no substrates are CTP and UTP [3,7] <2> no substrates are dTTP and AMP-PNP [3] <4> no substrates are bovine serum albumin and calf thymus histone [7] <5> no substrate is phosvitin... 

Krane, S. M., Stone, M. J., Glimcher, M. J. The presence of protein phosphokinase in connective tissues and the phosphorylation of enamel protein in vitro. Biochim. Biophys. Acta 97, 77 (1965)... 

Numerous enzymes are inhibited by flavones and flavonols. They include hydrolases, oxidoreductases, DNA synthetases, RNA polymerases, phosphatases, protein phosphokinases, oxygenase, and amino acid oxidases. In some cases, the type of inhibition is competitive, but more often it is allosteric. The stunning variety of the types of enzymes, the activities of which are influenced by flavonoids, spans across almost all enzyme classes. The enzymes summarized in Table 59.3 are not exhaustive and aims to familiarize the reader with the extent of enzyme modulatory activities recorded. 

As will be described later, the kinetics of appearance of enzymes in vitro correspond well to the kinetics in vivo (Fig. 2). Together with other methods, in vivo kinetics helped to map various other genes in the left-side section of T7 DNA the genes for the translational-repressor, for the RNA shut-off function, the protein phosphokinase and a phospholipid synthesizing activity (Schweiger et al., 1972 Herrlich et al., 1973 and 1974 Rahmsdorf et al., 1973 and 1974). 

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