Presence of a DNA demethylating activity in the nucleus of murine erythroleukemic cells.

摘要: Nucleoplasm prepared from murine erythroleukemia cells was assayed enzymatic activity which removes methyl groups DNA methylated at the internal C of sequence 5'-CCGG-3' (Hpa II sites). Under conditions assay, release linear with time for 1 h, and up to 2 pmol could be released per microgram extract protein. The proportional amount added sensitive heat ant proteinase K exposure. initial velocity hyperbolic increasing amounts substrate, Km estimated between 1.5 microM. These results show that demethylation catalyzed by extracts cell nuclei can occur in vitro where no synthesis is occurring suggest such a process might vivo alter methylation during differentiation.