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)

Retroviruses carry cell-derived oncogenes (v-onc) that have the potential to transform cells in culture and induce tumours in vivo. One of the few carcinoma-inducing viruses is the acutely transforming retrovirus MH2, which carries the putative oncogene v-mil and the known oncogene v-myc. Recently, a high degree of homology was discovered between v-mil and v-raf, the transforming gene of the murine retrovirus 3611 murine sarcoma virus (MSV), whereas homology to v-src is low. Both viruses express their oncogenes as the gag-fusion polyproteins p100gag-mil and p75gag-raf (of respective relative molecular mass (Mr) 100,000 and 75,000), while the myc oncogene of MH2 is expressed by means of a subgenomic messenger RNA. We have recently demonstrated that p100gag-mil is not a nuclear protein. Here we report that purified p100gag-mil and p75gag-raf exhibit protein kinase activities in vitro which, in contrast to the src-related p130gag-fps of Fujinami sarcoma virus (FSV) and all other characterized oncogene-encoded protein kinases, phosphorylate serine and threonine but not tyrosine. Both types of protein kinases phosphorylate lipids in vitro.
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PMID:Serine- and threonine-specific protein kinase activities of purified gag-mil and gag-raf proteins. 643 34

Relative to resting liver, Morris hepatomas with different growth rates (3924A, 5123D, 7800, and 7777) all had higher (two to eightfold) levels (activity/gm tissue) of RNA polymerase I. Only the most rapidly growing tumor (hepatoma 3924A) showed a substantial increase (fivefold) in RNA polymerase III activity. RNA polymerase II activity/gm tissue in the hepatomas was similar to that in resting liver. The elevation in the hepatoma RNA polymerase I activity resulted from both an increase in the number of transcriptionally active enzyme molecules and an increase in the specific activity of the enzyme as a result of phosphorylation. Phosphorylation of RNA polymerase I from Morris hepatoma 3924A could be catalyzed either by an endogenous protein kinase or by a highly purified preparation of NII protein kinase from the same tumor. Three out of eight polypeptides (Mr 120,000, 65,000, and 25,000) or RNA polymerase I were phosphorylated. Phosphorylation resulted in enhanced RNA synthesis at the level of chain elongation. Another nuclear protein kinase, NI, had no significant effect on RNA polymerase I. The activity and/or amount of the NII protein kinase was significantly reduced in resting liver, which correlated with decreased specific activity of the liver RNA polymerase I. Anti-RNA polymerase I antibodies were found in the sera of patients with rheumatic autoimmune diseases such as systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), and rheumatoid arthritis (RA). Sera from these patients were capable of specifically inhibiting RNA polymerase I activity in vitro. Antibodies were produced predominantly against three of the polypeptides--S3 (Mr 65,000), S4 (Mr 42,000), and S5 (Mr 25,000) of RNA polymerase I. The spectrum and proportion of the antibodies against these three subunits differ with each patient and with the type of the autoimmune disease. These observations indicate that (1) the NII kinase can regulate RNA polymerase I activity, (2) protein kinase NII is associated with the polymerase I enzyme complex, and (3) certain polypeptides of this enzyme complex may be the target antigens in rheumatic autoimmune disease.
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PMID:Regulation of RNA polymerase I by phosphorylation and production of anti-RNA polymerase I antibodies in rheumatic autoimmune diseases. 660 44

Particulate fractions prepared from concanavalin A-activated murine T lymphocytes contain an endogenous protein kinase that phosphorylates an endogenous protein substrate of Mr 112 000. The phosphorylation of 112 kDa protein is greatly reduced or absent in unstimulated T cells. Phosphoamino acid analysis indicates that 112 kDa protein is labeled on a serine. Add-back experiments using purified protein kinases indicate that 112 kDa protein serves as a substrate for casein kinase II. Phosphorylation of 112 kDa protein by the endogenous kinase is inhibited by heparin, a known casein kinase II inhibitor. The site or sites modified by the endogenous kinase and exogenous casein kinase II appear identical by peptide-mapping experiments. A time-course of the appearance of phosphorylated 112 kDa protein following stimulation with concanavalin A, measured in the presence or absence of added casein kinase II, suggests that 112 kDa protein is induced in activated T cells. Subcellular localization studies suggest that 112 kDa protein is a nuclear protein. Silver-binding and purification studies suggest that 112 kDa protein is of the nucleolar organizing region.
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PMID:Induction of a substrate for casein kinase II during lymphocyte mitogenesis. 660 22

Antibodies against nuclear protein kinase NII were detected by radioimmunoassay in the sera of patients with systemic lupus erythematosus and mixed connective tissue disease but not in sera from normal individuals or from patients with rheumatoid arthritis. Immunoglobulins derived from sera containing the anti-kinase antibodies inhibited the activity of protein kinase NII in vitro but had no effect on the activity of cytoplasmic cyclic AMP-dependent protein kinase.
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PMID:Anti-protein kinase NII antibodies in rheumatic autoimmune diseases. 669 57

RNA polymerase II was purified from Morris hepatoma 3924A by a series of ion-exchange and affinity column chromatographic fractionations, followed by sucrose gradient centrifugation in the presence of 0.3 M KC1. Purified RNA polymerase II had a specific activity of greater than 400 nmol of UMP incorporated (30 min)-1 (mg of protein)-1 by using double-stranded DNA as template. The purified enzyme contained five polypeptides (Mr 214 000, 140 000, 33 000, 25 000, and 21 000) that were present in molar quantities and two additional polypeptides (Mr 19 000 and 18 000) that had a combined molar ratio of 1.0. The cyclic AMP independent nuclear protein kinase NII, also purified from hepatoma 3924A, was able to phosphorylate RNA polymerase II polypeptides of Mr 214 000, 140 000, and 21 000. Phosphorylation of the polymerase was accompanied by enhanced transcription of double-stranded DNA, heat-denatured DNA, and poly[d-(A-T)]. The elevation in RNA polymerase activity was dependent upon the presence of hydrolyzable ATP and resulted from an increased number of RNA molecules synthesized in vitro. The average length of RNA chains was not affected by the kinase. Under similar conditions, protein kinase NII also stimulated homologous RNA polymerase I. In contrast to the phosphorylation of polymerase II, modification of polymerase I resulted in an increase in the average size, but not number, of RNA chains synthesized. The specificity of the NII kinase-catalyzed reaction was demonstrated by the inability of another homologous protein kinase, NI, to phosphorylate or activate RNA polymerase II.
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PMID:Phosphorylation of deoxyribonucleic acid dependent RNA polymerase II by nuclear protein kinase NII: mechanism of enhanced ribonucleic acid synthesis. 711 96

Protein kinase activity (EC 2.7.1.37) of buffalo spermatozoa is distributed in the head (22%) and midpieces + tails (74%). Extraction of sperm heads with 0.1% Triton X-100 solubilized 35--40 of the protein kinase activity and the remaining 60--65% was associated tightly with the sperm chromatin. That the sperm chromatin preparation was pure was established by recording its spectrum at 320/260 nm (0.07), determining its composition (protein:DNA ratio, 0.79), electron microscope examination and through the assay of marker enzymes. Extraction of the chromatin preparation with 1 M-NaCl only partly solubilized the protein kinase activity while treatment with DNase in the presence of dithiothreitol inactivated the nuclear protein kinase. The chromatin-associated protein kinase activity had a broad pH optimum (7.6--8.4), an essential requirement for Mg2+ and ATP as a phosphate donor. Histones and non-histone proteins served as substrates, the preferred substrate being arginine rich histone VIII followed by casein and phosvitin. Nuclear protein kinase activity was neither stimulated by cyclic AMP nor inhibited by purified muscle protein kinase inhibitor. It is suggested that chromatin-associated protein kinase (Type III protein kinase) may be involved in the control of DNA-template activity.
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PMID:Association of buffalo sperm protein kinase with sperm chromatin. 712 Jan 98

In nuclei and nucleoli of the slime mold Physarum polycephalum, ornithine decarboxylase (OrnDCase) (Mr 70,000) is phosphorylated by a protein kinase reaction that is dependent on spermidine and spermine. Putrescine antagonizes the phosphorylation. Phosphorylation of OrnDCase inhibits its capacity to catalyze decarboxylation of ornithine. The protein kinase that catalyzes this phosphorylation has many properties similar to those of nuclear protein kinase II, or type G, which has been studied by other groups. The interaction of this protein kinase with OrnDCase resembles the behavior of the OrnDCase antizyme described by other investigators. Phosphorylated OrnDCase binds to purified, palindromic rDNA isolated from nucleoli. It also stimulates transcription of the ribosomal genes by RNA polymerase I in a chromatin form of rDNA. It does not stimulate transcription in a purified, homologous transcription system comprised of RNA polymerase I, rDNA, and phospho-OrnDCase. Thus, phospho-OrnDCase may have a function in promoting rRNA gene transcription but the detailed mechanism is yet unclear. The polyamine-dependent protein kinase and its natural substrate of 70,000 daltons have been demonstrated in other eukaryotic cells, including bovine spermatozoa and rat liver nuclei, and in Ehrlich ascites tumor cells, where the protein kinase is induced by interferon. This phosphorylation system appears to be widely distributed and conserved among eukaryotic species.
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PMID:Posttranslational control of ornithine decarboxylase by polyamine-dependent protein kinase. 714 Oct 3

A cyclic-nucleotide independent heparin-sensitive nuclear protein kinase (NII) from the Morris hepatoma 3924A has been purified by a combination of ion exchange and affinity chromatographic procedures and velocity gradient centrifugation. The purified kinase had a molecular weight of 140,000 as determined by gel filtration. Two polypeptides (Mr = 42,000 and 25,600) were present in the purified preparation in approximately equimolar concentrations. The protein kinase employed Mg2+ and Co2+ as divalent ion and preferred the nonhistone proteins, casein or phosvitin, as protein acceptors. In the presence of Mg2+, it utilized both ATP and GTP as substrates and transferred the terminal nucleotide phosphate to serine and threonine residues of the protein acceptor. Phosphorylation of casein was stimulated by polyamines, particularly spermine. This polyamine preferentially enhanced phosphate transfer to threonine. The enzyme was inhibited by several compounds including heparin, the o-n-octyloxime of rifamycin (AF/013), 3'-dATP, o-phenanthroline, polynucleotides, and ADP. Of these inhibitors, heparin was the most potent and completely abolished kinase activity at a concentration of 0.1 micrograms/ml. The kinase could be autophosphorylated by incubation with Mg2+ and [gamma-32P]ATP; under these conditions phosphorylation was confined to the polypeptide of Mr = 24,600 and was completely inhibited by heparin. Based on the unique properties of NII protein kinase (ability to use GTP, stimulation by spermine, sensitivity to heparin), a selective assay was developed which could measure NII activity in the presence of other nuclear kinases. Under the optimal assay conditions, the nuclear extract of hepatoma 3924A was found to contain at least five times more NII kinase activity than that of normal adult liver. Analysis of extensively purified preparations from the two sources confirmed these results. After purification 11 times more NII protein kinase activity was obtained from hepatoma 3924A than from liver. Although hepatoma and liver protein kinases exhibited many common properties, they displayed distinct nucleotide saturation kinetics. The apparent Km for ATP was 10 microM for hepatoma protein kinase and 24 microM for the liver enzyme.
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PMID:A heparin-sensitive nuclear protein kinase. Purification, properties, and increased activity in rat hepatoma relative to liver. 725 4

We have recently purified a cyclic nucleotide-independent, heparin-sensitive nuclear protein kinase (NII) from Morris hepatoma 3924A and demonstrated an apparent relationship of this kinase to the two subunits (Mr = 42,000 and 24,600) of RNA polymerase I. When homogeneous protein kinase NII was recombined with purified homologous RNA polymerase I containing limiting quantities of endogenous kinase, RNA synthesis was stimulated as much as 5-fold during a 90-min incubation. The enhanced RNA synthesis was due to an increase in the average RNA chain length; protein kinase did not alter the number of RNA molecules synthesized by the polymerase. Phosphorylation of RNA polymerase occurred at serine and threonine moieties. Unlike the NII kinase, purified homologous NI kinase did not phosphorylate RNA polymerase I and, as a result, did not alter transcription. These data indicate that 1) RNA polymerase I is activated by protein kinase NII, 2) endogenous protein kinase NII remaining with highly purified RNA polymerase I does not fully phosphorylate RNA polymerase I in vitro, and 3) protein kinase NII is capable of regulating RNA polymerase I activity by preventing premature termination of RNA chains.
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PMID:Activation of purified hepatoma RNA polymerase I by homologous protein kinase NII. 728 32

2Two types of protein kinase inhibitors present in rat liver nuclei have been partially purified and characterized. They are specific for the nuclear enzymes, being inert toward the protein kinases in the cytosol. One inhibitor is a 150,000 dalton, heat-labile, acidic protein; the other is a family of two oligonucleotides. Inhibitory activity in crude extracts becomes measurable only after complete removal of protein kinase activity by affinity chromatography (Farron-Furstenthal, F., and Lightholder, J.R. (1977) FEBS Lett. 84, 313). Initial separation of the inhibitor protein from the oligonucleotide inhibitors was achieved by filtration through an Amicon pressure cell. Further purification of the inhibitor protein was obtained by chromatography on ion exchangers and Bio-Gel. The oligonucleotides were purified by DEAE-cellulose chromatography and paper electrophoresis. The effects of the two types of inhibitors are additive. The 170 to 200% recovery of protein kinase activity after removal of the inhibitors from the initial extracts suggests that the inhibitors contribute in a quantitatively significant measure to the regulation of nuclear protein phosphorylation.
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PMID:Two naturally occurring inhibitors of nuclear protein kinase. 737 96


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