Showing papers by "Michael B. Sporn published in 1972"

RNA metabolism in tracheal epithelium: alteration in hamsters deficient in vitamin A.

Abstract: The electrophoretic pattern of RNA molecules that are synthesized in vitro in tracheal epithelium from hamsters deficient in vitamin A differs from that of RNA synthesized in normal, pair-fed control hamsters. There is less RNA of low electrophoretic mobility in the epithelial cells deficient in vitamin A. This alteration is reversed after the deficient animals have been treated with vitamin A.

Inhibition of RNA-dependent DNA polymerase by thymidylate derivatives.

Abstract: The effects of several thymidylate derivatives with reactive substituents on the RNA-dependent DNA polymerase of Rauscher murine leukemia virus were investigated. The reactive substituents include haloacetamido groups potentially capable of forming covalent bonds with the enzyme. The kinetics of inhibition with thymidine-3′,5′-di- m -bromoacetamidophenyl phosphate, the most active agent of the series, was competitive with poly(rA)·oligo(dT), the model primer-template used, and noncompetitive with the deoxynucleoside triphosphates. Preincubation of the virus with thymidine-3′,5′-di- m -bromoacetamidophenyl phosphate magnified the inhibition of DNA synthesis. Inhibition of the reactions directed by DNA templates, such as salmon sperm DNA and poly[d(A-T)], was comparable to that found with poly(rA)·oligo(dT). The inhibition of tumor virus DNA polymerase is not selective, since we observed comparable inhibition of a DNA-dependent DNA-polymerase partly purified from phytohemagglutinin-stimulated normal human blood lymphocytes.

2'-O-methylation of adenosine, guanosine, uridine, and cytidine in RNA of isolated rat liver nuclei.

Abstract: Nuclei isolated from rat liver, when incubated with methyl-labeled S-adenosylmethionine, incorporated label into 2′-O-methyladenosine, 2′-O-methylguanosine, 2′-O-methyluridine, and 2′-O-methylcytidine of endogenous nuclear RNA. Addition of ribosomal RNA from wheat germ to the reaction markedly stimulated 2′-O-methylation of total RNA. The relative incorporation of label into the four different 2′-O-methyl ribonucleosides was greatly changed by the addition of wheat germ RNA. There was much more 2′-O-methylation of the purine ribonucleosides, relative to the pyrimidine ribonucleosides, in the reaction stimulated by wheat germ RNA.