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Title: (Accumulation of methyl-deficient rat liver messenger ribonucleic acid on ethionine administration). Progress report. [Methyltransferase activity in Ehrlich ascites tumor cells and effects of phorbol ester on methyltransferase activity]

Enzyme fractions were isolated from Ehrlich ascites cells which introduced methyl groups into methyl deficient rat liver mRNA and unmethylated vaccinia mRNA. The methyl groups were incorporated at the 5' end into cap 1 structures by the viral enzyme, whereas both cap 0 and cap 1 structures were formed by the Ehrlich ascites cell enzymes. Preliminary results indicate the presence of adenine N/sup 6/-methyltransferase activity in Ehrlich ascites cells. These results indicate that mRNA deficient in 5'-cap methylation and in internal methylation of adenine accumulated in rats on exposure to ethionine. The methyl-deficient mRNA isolated from the liver of ethionine-fed rats differed in its translational properties from mRNA isolated from control animals. Preliminary experiments indicate that single topical application of 17n moles of TPA to mouse skin altered tRNA methyltransferases. The extent of methylation was increased over 2-fold in mouse skin treated with TPA for 48 hours. These changes have been observed as early as 12 hours following TPA treatment. In contrast, the application of initiating dose of DMBA had no effect on these enzymes. It should be emphasized that the changes in tRNA methyltransferases produced by TPA are not merely an increase of the concentration of the enzyme, rathermore » that they represent alterations of specificity of a battery of enzymes. In turn the change in enzyme specificity can produce alterations in the structure of tRNA. (ERB)« less
Authors:
Publication Date:
OSTI Identifier:
5073185
Report Number(s):
DOE/EV/10100-1
DOE Contract Number:
AC02-79EV10100
Resource Type:
Technical Report
Research Org:
American Cancer Research Center and Hospital, Lakewood, CO. Dept. of Basic Oncology
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; ASCITES TUMOR CELLS; TRANSFERASES; ETHIONINE; BIOLOGICAL EFFECTS; MESSENGER-RNA; METHYLATION; ENZYME ACTIVITY; VACCINIA VIRUS; PHORBOL ESTERS; AMINO ACIDS; ANIMAL CELLS; ANIMALS; BODY; CARBOXYLIC ACIDS; CARCINOGENS; CHEMICAL REACTIONS; DISEASES; ENZYMES; ESTERS; EXPERIMENTAL NEOPLASMS; LIPOTROPIC FACTORS; MAMMALS; MICROORGANISMS; NEOPLASMS; NUCLEIC ACIDS; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANIC SULFUR COMPOUNDS; ORGANS; PARASITES; PROMOTERS; RNA; RODENTS; TUMOR CELLS; VERTEBRATES; VIRUSES 550200* -- Biochemistry; 550900 -- Pathology