Poly(A)-mRNA deprimerones in rat liver and Novikoff hepatoma cells.
The poly (A)-mRNA fraction isolated by chloroform deproteinization of liver polysomes and poly(U)-Sepharose chromatography contains a low molecular weights (congruent to 1000) peptidic fraction. The peptides which we suggested to call deprimerones (1) were extracted with 80% ethanol at pH 9.5; after ethanol evaporation, they were purified on Sephadex G-25 column as a fraction of mol. wt. between 1600 and 600, yielding about 9 mg/mg mRNA. If deproteinization is performed with phenol-chloroform the yield is about 2 mg/mg mRNA. In Novikoff hepatoma the yield of the same preparation is only 2.7 mg/mg mRNA (about 70% decrease). The obtained deprimerones are active in inhibiting transcription of thymus DNA with E. coli RNA polymerase and [3H]-GTP by about 90% at a ratio peptide/DNA = 2. For comparison the deprimerones obtained previously (2) by extraction of deproteinized DNA inhibit transcription only by about 50% at the same peptide/DNA ratio. The results demonstrated a decrease of the poly (A)-mRNA deprimerone level during carcinogenesis and further support the previously demonstrated specific occurrence of deprimerones with poly(A)-mRNA. They remain in accordance with and provide further support for the deprimerone theory of carcinogenesis postulated earlier (1).
D000818:Animals; D008099:Liver / Q000378:metabolism*; D008114:Liver Neoplasms, Experimental / Q000378:metabolism*; D008970:Molecular Weight; D010447:Peptide Hydrolases / Q000378:metabolism; D010455:Peptides / Q000378:metabolism* / Q000494:pharmacology; D011061:Poly A / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D013381:Subtilisins; D013552:Swine; D014158:Transcription, Genetic / Q000187:drug effects
D010455:Peptides; D012333:RNA, Messenger; C021657:deprimerones; D011061:Poly A; D010447:Peptide Hydrolases; D013381:Subtilisins