title: Partial purification and characterization of a new phosphoprotein kinase from cells infected with pseudorabies virus.
abstract: Cytoplasmic fractions from normal baby hamster kidney fibroblasts and from fibroblasts infected with pseudorabies virus were fractionated by DEAE-cellulose chromatography and fractions assayed for protein kinase activity. In preparations from uninfected and infected cells protein kinase activities identified as casein kinase I and II, the two isoforms of the cyclic-AMP-dependent protein kinase, protein kinase C, and a presumed proteolytic fragment of protein kinase C were present in comparable amounts. However in infected cells a new protein kinase activity was detected, appearing about 4 h after infection and increasing during the following 6 h at least. This new protein kinase was purified 100-fold by high-performance gel-permeation and ion-exchange chromatography, and characterized. It has an apparent relative molecular mass of 68 000 on the basis of gel-permeation chromatography, and a sedimentation coefficient of 4.3 S. It catalysed the phosphorylation of serine residues of basic proteins in vitro, with protamine a better substrate than mixed histones; and used ATP (apparent Km = 60 microM), but not GTP, as phosphoryl donor. Molecules that can serve as effectors for other protein kinases (cyclic AMP, cyclic GMP, Ca2+ + calmodulin, Ca2+ + phospholipid, double-stranded RNA, and heparin) did not significantly alter the activity of this enzyme. A distinguishing characteristic of the protein kinase was a high KCl concentration optimum with the persistence of activity up to 800 mM KCl, at least.
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D006224:Cricetinae; D008274:Magnesium / Q000494:pharmacology; D015636:Magnesium Chloride; D008970:Molecular Weight; D011189:Potassium Chloride / Q000494:pharmacology; D006656:Protamine Kinase / Q000378:metabolism; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D011557:Pseudorabies / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D015636:Magnesium Chloride; D011189:Potassium Chloride; D011494:Protein Kinases; D006656:Protamine Kinase; D008274:Magnesium