S-adenosylmethionine: DNA-cytosine 5-methyltransferase from a Novikoff rat hepatoma cell line

Deficiency of S-adenosylmethionine-homocysteine methyltransferase activity in hepatoma cells.

S-Adenosylmethionine-homocysteine methyltransferase, which catalyzes synthesis of methionine from homocysteine, with the use of S-adenosylmethionine as the methyl donor, is absent in tumor tissue such as rat ascites hepatoma and Morris hepatoma but is present in rat liver homogenate. Absence of the enzymatic activity in tumor cells is not due to the action of an inhibitor. S-Adenosylhomocystein...

DNMT 1 ( DNA ( cytosine - 5 - ) - methyltransferase 1 ) )

DNA ( cytosine - 5 ) - methyltransferase 1 - [ Isoform 1 ]

The murine equivalent of the human DNMT1 (DNA [cytosine-5]-methyltransferase 1; Swiss-Prot accession number: P26358) gene was deleted in ES cells via gene targeting [1]. Dnmt1-/cells possessed dramatically decreased genomic methylation and were viable; however, the mutation caused a homozygous lethal phenotype when introduced into the germline (see Table of experimental models for DNMT1) [1]. C...

Purification of thioredoxin from rat Novikoff ascites hepatoma.

Partial purification of a thioredoxin system from Novikoff ascites hepatoma cells has been previously reported (MOORE, E. C. (1967) Biochem. Biophys. Res. Commun. 29, 264-268). Thioredoxin from the same mammalian source has now been purified to electrophoretic homogeneity by ammonium sulfate fractionation, heat treatment, DEAE-cellulose chromatography, and Sephadex chromatography. 1-Dimethylami...

Stimulation of DNA polymerase by factors isolated from Novikoff hepatoma.

Extracts of Novikoff hepatoma cells contain factors capable of stimulating in vitro DNA synthesis several fold. The activity can be resolved into three separate protein peaks on DEAE-Sephadex. Two of these, factors II and III, have been purified and partially characterized. Both factors increase the initial rate of DNA synthesis and allow synthesis to proceed much longer. If either factor is ad...