Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To ascertain the activity and substrate specificity of nuclear protein kinases during various stages of the cell cycle of HeLa S3 cells, a nuclear phospho-protein-enriched sample was extracted from synchronised cells and assayed in vitro in the presence of homologous substrates. The nuclear protein kinases increased in activity during S and G2 phase to a level that was twice that of kinases from early S phase cells. The activity was reduced during mitosis but increased again in G1 phase. When the phosphoproteins were separated into five fractions by cellulose-phosphate chromatography each fraction, though not homogenous, exhibited differences in activity. Variations in the activity of the protein kinase fractions were observed during the cell cycle, similar to those observed for the unfractionated kinases. Sodium dodecyl sulfate polyacrylamide gel electrophoretic analysis of the proteins phosphorylated by each of the five kinase fractions demonstrated a substrate specificity. The fractions also exhibited some cell cycle stage-specific preference for substrates; kinases from G1 cells phosphorylated mainly high molecular weight polypeptides, whereas lower molecular weight species were phosphorylated by kinases from the S, G2 and mitotic stages of the cell cycle. Inhibition of DNA and histone synthesis by cytosine arabinoside had no effect on the activity or substrate specificity of S phase kinases. Some kinase fractions phosphorylated histones as well as non-histone chromosomal proteins and this phosphorylation was also cell cycle stage dependent. The presence of histones in the in vitro assay influenced the ability of some fractions to phosphorylate particular non-histone polypeptides; non-histone proteins also appeared to affect the in vitro phosphorylation of histones.
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PMID:Nuclear protein kinase activities during the cell cycle of HeLa S3 cells. 51 84

Reuber H 35 hepatoma cells were synchronized by transfer in a serum free medium. Growth was re-initiated by addition of serum. Under these conditions DNA synthesis exhibited a maximum after 24 hours. Chromatin non-histone proteins prepared from cells at various phases of the cell cycle were incubated with [gamma-32P] ATP and the radioactive pattern of protein bound 32P was analysed by electrophoresis on polyacrylamide gels. No radioactive peak was observed in G0. Several peaks appeared 3 hours after the addition of serum. The radioactivity progressively increased until the cells reached the S phase. When most of the cells were in the S phase the radioactivity strongly decreased. Chromatin protein kinase activities were found to increase in late G1 and continued to increase in the S phase. The increase was 65% when phosvitin was the substrate, 100% with casein and histone H1. It is suggested that chromatin phosphorylated proteins could be involved in the mechanism which initiates DNA synthesis in G1 phase cells.
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PMID:Variations in some molecular events during the early phases of the Reuber H 35 cell cycle. II.-Chromatin protein phosphorylation and protein kinases. 51 30

HeLa chromatin core particles contain a protein kinase which transfers phosphate from ATP to both nonhistone proteins and histones. The enzyme preferentially modifies H3 among the histones; about 7% of the H3 molecules in the nucleoprotein are modified at saturation. Activity of this kinase likely contributed to earlier results using crosslinking methodology to study which histones interact with the ends of core particle DNA. When the kinase is largely removed by sedimentation of core particles through sucrose gradients containing 0.45 M NaCl, crosslinking of the 5'-terminal label on DNA is observed only to histone H3. The overall efficiency of the crosslinking reaction is about 15%. The origin of the 5'-terminal 32P previously assigned as crosslinked to H4 is not explained by the current experiments.
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PMID:Protein kinase in HeLA nucleosomes: a reevaluation of the interactions of histomes with the ends of core particle DNA. 65 16

Deletion and point mutants of T3 have been isolated and used to show that the early region of T3 DNA is organized in the same way as that of T7 DNA. Homologous early RNAs and proteins of the two phages have been identified by electrophoresis on polyacrylamide gels in the presence of sodium dodecyl sulfate. Both phages have five early mRNA's, numbered 0.3, 0.7, 1,1.1 and 1.3 from left to right, although no T3 protein that corresponds to the 1.1 protein of T7 has yet been identified. In general, corresponding early RNAs and proteins of the two phages migrate differently on gels, indicating that they differ in molecular weight and/or conformation. In both T7 and T3, gene 0.3 is responsible for overcoming the DNA restriction system of the host, gene 0.7 specifies a protein kinase, gene 1 specifies a phage-specific RNA polymerase, and gene 1.3 specifies a polynucleotide ligase. The 0.3 protein of T3 is responsible for the S-adenosylmethionine cleaving activity (SAMase) induced after T3 (but not T7) infection. However, cleaving of S-adenosylmethionine does not appear to be the primary mechanism by which T3 overcomes host restriction, since at least one mutant of T3 has lost the SAMase activity without losing the ability to overcome host restriction.
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PMID:SAMase gene of bacteriophage T3 is responsible for overcoming host restriction. 78 4

A protein of 30000-35000 molecular weight was isolated from mouse ascites cells. This protein binds preferentially to single-stranded DNA. Evidence is presented that this protein maintains single-stranded DNA in an extended configuration. In the presence of single-stranded template the protein stimulates mammalian DNA polymerase alpha but not the mammalian DNA polymerase beta and not some microbial DNA polymerases. The protein is phosphorylated in vitro by a chromatin-associated protein kinase. The modified DNA-binding protein does not stimulate the DNA polymerase alpha.
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PMID:A single-strand-specific DNA-binding protein from mouse cells that stimulates DNA polymerase. 83 35

A specific ribosome-associated protein kinase (protein kinase II) and phosphoprotein(s) from the ribosomal KCl wash fraction termed "PPx" have been isolated from plasmacytoma, and tested for their ability to bind to poly(A) and to different plasmacytoma polynucleotides. The nitrocellulose filter binding technique was used to measure RNA-protein interaction. Protein kinase II and PPx preferentially bound mRNA compared to poly(A). They did not bind ribosomal RNA, soluble RNA or DNA. The optimal conditions (temperature, time, protein concentration, ionic strength) for mRNA-protein interaction were determined. Ribosomal protein kinase (protein kinase II) phosphorylated PPx proteins which bound to mRNA represented at least two bands as determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (Mr = 90 000 and 80 000). The high affinity of protein kinase II and PPx for mRNA suggests that they may function in regulating protein synthesis.
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PMID:Messenger RNA binding of a ribosome-associated protein kinase and a ribosomal phosphoprotein(s) in mouse plasmacytoma. 88 30

The nonhistone proteins of Ehrlich ascites tumor chromatin have been separated into a loosely bound and two tightly bound protein fractions by sequential extraction of chromatin with 0.35 M NaCl and 2 M NaCl:5 M urea. The nonhistone proteins thus obtained were examined for their chemical composition and distribution of DNA polymerase, RNA polymerase, and protein kinase activities. In addition, the effect of these nonhistone proteins on transcription of DNA in vitro has been determined. The results indicate that these nonhistone proteins, fractionated on the basis of their extractability, exhibit varied compositional characteristics and play different functional roles in the synthesis of DNA and RNA and in the possible control of gene activity.
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PMID:A comparison of the loosely bound and tightly bound nonhistone proteins from Ehrlich ascites tumor chromatin. 97 79

A novel protein kinase that requires protamine as an activator to catalyze the phosphorylation of viral acceptor proteins was extracted from vaccinia virus cores with deoxycholate and purified 250-fold by DNA-cellulose and DEAE-cellulose column chromatography. The enzyme has a molecular weight of 62,000 as determined by sucrose gradient sedimentation. Two heat-stable phosphate acceptor proteins were extracted from virus particles with a nonionic detergent and purified by heat treatment, precipitation with organic solvents, and CM-cellulose chromatography. The molecular weights of the phosphate acceptor proteins, determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis, are 38,500 and 11,700.
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PMID:Purification of a protein kinase and two phosphate acceptor proteins from vaccinia virions. 112 20

DNA-dependent RNA polymerase A (or 1) was purified from murine myeloma MOPC 21 by diethylaminoethyl Sephadex chromatography. Further separation from DNA polymerases, protein kinase and DNA endonuclease was accomplished by polyriboadenylate-Sepharose affinity chromatography followed by gradient centrifugation. Yields following chromatography were 100%, but following gradient centrifugation only 25 to 30% of the activity remained. Addition of low-molecular-weight components increased yields to 50 to 60%. Several species of myeloma polymerase A could be detected, and subunits of 190,000 and 125,000 daltons were identified. No evidence of phosphorylation of the polymerase was found.
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PMID:Purification, analysis, and subunits of myeloma (MOPC 21) DNA-dependent RNA polymerase A (1) by polyriboadenylate-sepharose. 125 70

Incorporation of labeled thymidine into testicular DNA of hypophysectomized rats began to increase after the administration of testosterone propionate and choriogenic gonadotrophin. While the thymidine incorporation reached maximum in 4 days, the DNA polymerase activity did not culminate until 8 days after the initiation of hormone treatment. The high molecular weight (6--8 S), presumably cytoplasmic DNA polymerase accounted almost entirely for this increase. Administration of testosterone propionate and chorionic gonadotrophin to hypophysectomized rats results in an increase of testicular RNA polymerase and chromatin templating activity. Chain elongation and initiation studies revealed that the increased templating capacity of androgen-stimulated testicular chromatin was almost entirely caused by the increase in the number of initiation sites. While the nuclear polymerase I responded relatively rapidly to hormone stimulation and reached a prominent maximum in about three days, the activity of polymerase II was more sluggish and not as prominent. The in vivo incorporation of ortho[32P]phosphate into chromosomal phosphoproteins occurred early during the androgen treatment and reached a maximum in about 20 h. The protein phosphokinase activity peaked later, approx. 72 h after the first administration of hormones.
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PMID:Testicular chromatin activation in hypophysectomized rats. 127 99


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