These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Demonstration of normal and mutant protein M1 subunits of deoxyGTP-resistant ribonucleotide reductase from mutant mouse lymphoma cells.
    Author: Ullman B, Gudas LJ, Caras IW, Eriksson S, Weinberg GL, Wormsted MA, Martin DW.
    Journal: J Biol Chem; 1981 Oct 10; 256(19):10189-92. PubMed ID: 7024266.
    Abstract:
    From a mutagenized population of mouse T-lymphoma cells (S49) in continuous culture a cell line has been isolated (Ullman, B., Gudas, L. J., Clift, S. M., Martin, D. W., Jr. (1979) Proc. Natl. Acad. Sci. U. S. A. 76, 1074-1978) with ribonucleotide reductase activity that is inhibited only 50% by concentrations of dGTP which abolish wild type enzyme activity. Ribonucleotide reductase activity from this dGuo-L cell line retains its normal sensitivity to dATP. The partial sensitivity/partial resistance of the ribonucleotide reductase suggests that the dGuo-L cell line is heterozygous for ribonucleotide reductase, possessing one normal allele and one allele which codes for a dGTP-resistant enzyme. Both homologous and heterologous mixing experiments between the separated nonidentical subunits of ribonucleotide reductase, protein M1 and protein M2, from wild type and dGuo-L cells showed that the dGTP- feedback sensitivity was governed by the source of the protein M1. A partial resolution of two dGuo-L protein M1 components was achieved by chromatography on dextran blue-Sepharose. In order to resolve the two dGuo-L protein M1 components more completely, we introduced into dGuo-L cells a second mutation which conferred resistance of the ribonucleotide reductase to dATP, while the original dGTP resistance was maintained. The chromatography of protein M1 from this latter clone, dGuo-L-Aphid-G5, on dATP-Sepharose resolved two kinetically distinct protein M1 components. The first component was sensitive to dGTP inhibition but stimulated by dATP; the second was absolutely refractory to dGTP but sensitive to dATP inhibition. This confirms the hypothesis that the dGuo-L parent is heterozygous for protein M1, containing one wild type and one mutant allele.
    [Abstract] [Full Text] [Related] [New Search]