pactamycin and Carcinoma--Ehrlich-Tumor

Topics: Animals; Antibiotics, Antineoplastic; Carcinoma, Ehrlich Tumor; Cycloheximide; Dactinomycin; DNA Polymerase I; DNA-Directed DNA Polymerase; Dose-Response Relationship, Drug; Kinetics; Mice; Pactamycin; RNA, Ribosomal; Transcription, Genetic

Topics: Animals; Carcinoma, Ehrlich Tumor; Cell-Free System; Encephalomyocarditis virus; Hydrolysis; Kinetics; Pactamycin; Peptide Chain Initiation, Translational; Poly A; Protein Biosynthesis; RNA, Messenger; RNA, Viral

A high speed supernatant fraction from wheat germ was shown to be a very effective inhibitor of protein synthesis in a cell-free protein synthesizing system from Ehrlich ascites cells. Low concentrations of the extract were equally effective in inhibiting the translation of EMC viral RNA, ascites cell mRNA (exogenous) and endogenous mRNA. The kinetics of inhibition in the presence and absence of pactamycin, as well as the observed inhibition of polyphenylalanine synthesis, indicate that the wheat germ inhibitor acts at the level of elongation. Preincubation of the ascites system with the wheat germ inhibitor in the presence and absence of ATP showed that ATP was required for the development of the inhibition. The inhibitor was partially purified and appears to be a basic protein with a molecular weight of 30 000--40 000. These results are discussed with respect to the hypothesis that this may be another example of a protein kinase-induced inhibition of protein synthesis.

Topics: Adenosine Triphosphate; Animals; Carcinoma, Ehrlich Tumor; Kinetics; Mice; Neoplasm Proteins; Pactamycin; Plant Proteins; Poly U; Protein Biosynthesis; Seeds; Triticum

Topics: Animals; Carbon Radioisotopes; Carcinoma, Ehrlich Tumor; Electrophoresis, Polyacrylamide Gel; Kinetics; Pactamycin; RNA, Ribosomal; Tritium; Uridine