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:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Metallothioneins that bind copper and zinc have an Mr of 6500 daltons, consist of a single polypeptide chain of 61 amino acids, 25-30 percent of whose residues are cysteine, have a metal-binding capacity of between 5 and 7 g atoms/mol, and contain no disulfide bonds or aromatic amino acids. Zincthionein has been postulated to participate in the transport and storage of zinc, which is involved in more than 235 metalloenzymes, including thymidine kinase, RNA polymerase, and ribonuclease, which in turn play crucial roles in the replication and transcription of DNA during cell division. In addition, trace elements including zinc modulate immune response and function. Conversely, zinc deficiency state causes, for example, thymic atrophy and lymphopenia and modifies antibody-mediated responses to both T-cell-dependent and T-cell-independent antigens. The concentrations of copper, zinc, and metallothionein and the copper/zinc ratio are modified in a number of malignancies. For example, the levels of metallothionein in normal and in malignant human livers are 471 and 75 micrograms/g, respectively. In addition, the copper/zinc ratio is significantly increased in human pancreatic cancer from 1.40 to 2.70. Furthermore, studies involving 64Cu in tumor-bearing mice showed that the distribution of 64Cu was altered and that all tumors contained a relatively high level of 64Cu. Moreover, the activity of superoxide dismutase to remove free oxygen radicals is lower in malignant tissues. Finally, the results of clinical studies suggest that the monitoring of the serum copper/zinc ratio may be a valuable tool, not only in determining the extent of malignancies, but also in predicting the efficacy of treatments.
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PMID:The status of zinc, copper, and metallothionein in cancer patients. 328 43

Tumor antigen (T-antigen) of simian virus 40 (SV40) has been shown to have a number of regulatory roles in both viral replication and early viral transcription. However, the nature of its role on late viral transcription remains unclear. We have analyzed for the presence of T-antigen on SV40 late viral transcription complexes which exhibit RNA polymerase II extension activity in vitro. Nuclear extract or glycerol gradient-isolated transcription complexes were treated with either polyclonal or monoclonal antibodies, and the amount of extension activity that could be immunoprecipitated was determined. Anti-T antibody derived from hamster ascites as well as the anti-T monoclonal antibodies PAb 102, 109, 416, and 419 all precipitated 12-29% of viral transcription complex activity. Immunoprecipitation resulted in significant enrichment of transcription complex activity relative to bulk minichromosomes, indicating a preferential association of T-antigen with the late viral transcription complex. This is the first direct demonstration of the presence of T-antigen on the SV40 late transcription complex. Furthermore, the immunoprecipitated transcription complexes exhibited a salt dependence of their in vitro extension activity which was distinct from that of the total complex population, indicating that T-antigen is present on a specific subclass of transcription complexes.
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PMID:Immunoprecipitation of the simian virus 40 late transcription complex with antibody against T-antigen. 331

Complementary DNA (cDNA) clones encoding a transcription factor S-II were isolated and characterized. The primary structure of S-II was determined by nucleotide sequence analysis of these clones. The predicted primary structure was consistent with the model that we proposed previously from the results of biochemical analyses of S-II. Using these clones as probes, we analyzed the mRNA for S-II. RNA blot analysis demonstrated the presence of four species of mRNA that hybridized with S-II cDNA in Ehrlich ascites tumor cells. This is the first evidence of polymorphism of mRNA encoding a transcription factor of RNA polymerase II. The results of analysis of the genomic structure suggested that the polymorphism of mRNA may be due to alternative splicing, or differences in initiation or termination of transcription.
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PMID:Molecular cloning and characterization of cDNA for eukaryotic transcription factor S-II. 334 29

Elevated protein synthesis in mouse tumor-host liver is the net result of both stimulatory and inhibitory responses. This study compares the directional change in transcription and synthesis of liver and plasma proteins in tumor-host liver as compared with para-neoplastic conditions, such as malnutrition, inflammation, benign cell proliferation and protein deficiency. A methylcholanthrene-induced sarcoma was used in weight stable mice (C57BI/6J). Inflammation was induced by s.c. turpentine injection, and benign cell proliferation by injection of heat-killed Corynebacterium parvum. DNA-dependent RNA-polymerase activity (I, II and III) (EC2.7.7.6) was measured in isolated hepatic nuclei. Protein synthesis was measured by labelling of hepatic and plasma proteins following the injection of a "flooding dose" of the labelled amino acid. Benign hepatic cell proliferation and sterile inflammation caused increased rates of transcription, while malnourished and healthy control animals had lower hepatic transcription than animals bearing a malignant tumor. Inflammation was associated with increased activities of free (nonchromatin engaged) RNA polymerase, which was not found in any other para-neoplastic condition or in the tumor-host liver. A protein- and calorie-deficient state was associated with depressed hepatic and plasma protein synthesis compared with the tumor condition. Tumor-host livers had a nonsecretory protein synthesis rate equal to that of normal livers, but 45% higher plasma protein synthesis. Animals with inflammation and benign cell growth had liver protein synthesis rates which were approximately 50% higher than in tumor-bearing animals, but plasma protein synthesis in tumor-bearing animals was comparable with that of animals which had inflammation. Benign cell growth was not associated with an overall elevated plasma protein synthesis. The translation rate per transcription activity was highest in normal animals and decreased in animals suffering from either tumor, protein deficiency or benign cell proliferation. Hepatic protein synthesis in tumor-host livers is high considering the degree of anorexia and malnutrition, although not as high as in livers from animals with pronounced inflammation. This counter-regulation in tumor-host livers may indicate a compensatory state to maintain protein synthesis against attenuating factors such as the declining food intake. Protein metabolism in tumor-host livers represents an unusual combination of findings.
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PMID:RNA polymerase activity and protein synthesis in mouse tumor-host liver compared to benign para-neoplastic reactions. 341 72

Retinoids are effective inhibitors of chemical carcinogenesis in the skin, mammary gland, esophagus, respiratory tract, pancreas, and urinary bladder of experimental animals. Modification of the basic retinoid structure has produced retinoids with enhanced target organ specificity, resulting in increased anticancer activity with reduced systemic toxicity. Newer retinoidal benzoic acid derivatives are even more active. Combining retinoid treatment with other modulators of carcinogenesis results in a synergistic inhibition of tumor development. Retinoids in combination with hormonal manipulation are much more effective in inhibiting mammary carcinogenesis than is either treatment alone; this combination approach also inhibits mammary tumor recurrence following surgical removal of the first tumor. Retinoids are most effective when administered shortly after the carcinogenic insult. However, even when retinoid treatment is delayed, the compounds are still effective cancer chemopreventive agents for the mammary gland and urinary bladder. The time that retinoid exposure can be delayed and retain an anticancer effect is directly related to tumor latency, with a longer delay permissible against tumors with long latent periods. The mechanism(s) by which retinoids inhibit carcinogenesis is unknown; however, in the mammary gland, retinoids inhibit differentiation and proliferation, DNA synthesis, and RNA polymerase activity. Cytosolic retinoid-retinoid receptor complexing is apparently a prerequisite for the nuclear interaction of retinoids, at least in mammary cells.
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PMID:Anticarcinogenic effects of retinoids in animals. 359 31

The activity of ornithine decarboxylase in androgen-dependent mouse mammary tumor (Shionogi Carcinoma 115) was reduced to 25% by castration of tumor-bearing mice and restored to the normal level 12 h after administration of testosterone or 5 alpha-dihydrotestosterone. Administration of estradiol-17 beta to the tumor-bearing castrated mice also stimulated the enzyme activity while progesterone and cortisol had little effect. On the other hand, the enzyme activity was affected by neither castration nor androgen injection to CS 2, which is a subline of SC 115 and completely independent of androgen for growth. The inhibition of ornithine decarboxylase activity in SC 115 by injecting alpha-difluoromethylornithine did not affect the enhancement of RNA polymerase I activity by androgen, showing independent elevation of the levels of the two enzymes by androgen.
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PMID:Effect of androgen on ornithine decarboxylase activity in androgen-dependent mouse mammary tumor (Shionogi Carcinoma 115) and its androgen-independent subline (CS 2). 375 19

A fraction containing a transcription factor(s) of RNA polymerase II was prepared from a nuclear lysate of Ehrlich ascites tumor cells and its binding to a promoter region of the adenovirus 2 major late gene was examined. Results showed that this fraction contained a factor(s) binding to two distinct regions: a region including the 'TATA' box and another region further upstream. The upstream protected region was different from that reported to be protected by a HeLa cell factor, suggesting species specificity of transcription factor(s) in DNA binding.
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PMID:Transcription factor(s) of Ehrlich ascites tumor cells having affinity to the 'TATA' box and a further upstream region of the adenovirus 2 major late gene. 379 May 68

Nuclear DNA-dependent RNA polymerases I, II and III were purified from kidney, liver and spleen from Swiss mice (Mus musculis) and from seven transplantable murine tumors. In the presence of the optimal concentration of (NH4)2SO4 for each polymerase, 1-8 mM spermidine or spermine stimulated most polymerases several fold, and generally, enzyme I was stimulated more than either enzyme II or III. Spermine was more efficacious than spermidine as a stimulant of polymerase activity except for polymerase III from three tumors. Tumor polymerases I (or II) and the corresponding normal tissue enzymes responded similarly to the polyamines. Stimulation of a RNA polymerase by a polyamine could not be correlated with the growth rate of the tissues of polymerase origin or with the tissue's RNA polymerase or RNA synthetic activities.
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PMID:Comparison of the effects of polyamines on the activities of RNA polymerases from murine normal tissues and transplantable tumors. 381 57

A factor that stimulates random transcription of purified DNAs by RNA polymerase II has been partially purified and analyzed with respect to its possible role in specific transcription from class II promoters. Studies of the effect of this factor (transcription factor IIS) on transcription from the adenovirus major late promoter in a system reconstituted with RNA polymerase II and purified factors (IIA, IIB, IIE, and IID) indicated that it acted subsequent to the initiation step and that it stimulated the rate of elongation. Kinetic experiments indicated that the factor affected the efficiency with which the RNA polymerase II passed through pausing sites. The relationship of transcription factor IIS to a protein previously purified from Erlich ascites tumor cells (Sekimizu, K., Nakanishi, Y., Mizuno, D., and Natori, S. (1979) Biochemistry 18, 1582-1588) was also studied.
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PMID:Factors involved in specific transcription by mammalian RNA polymerase II. Transcription factor IIS stimulates elongation of RNA chains. 381 44

The spatial arrangement of the subunits of RNA polymerase II from Ehrlich ascites tumor cells was investigated by measuring the sensitivity of each subunit in the native enzyme to various proteinases. The results showed that the largest two subunits (a and b) were sensitive to all the proteinases tested, whereas two smaller subunits (e and h) were resistant to these enzymes. These results suggest that in the native enzyme subunits e and h are located in the inside of RNA polymerase II, forming a core. It was also found that the conformation of the DNA binding subunit a changes when the enzyme binds to DNA, and it becomes much more susceptible to chymotryptic digestion.
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PMID:Conformational change of DNA binding subunit of RNA polymerase II on binding to DNA. 389 Aug 52


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