title: O6-methylguanine-DNA methyltransferase activity and sensitivity to N-methyl-N'-nitro-nitrosoguanidine during human T-lymphocyte differentiation.
abstract: The activity of O6-methylguanine-DNA methyltransferase (MT) was assayed in various human lymphoid cell populations. It was found that during T-cell differentiation the activity of MT increased from 7000 MT molecules in thymocytes to 31,000 MT molecules in mature T-lymphocytes. The number of MT molecules also increased 2- to 3-fold in the course of the cell division cycle but the specific activity of MT did not change significantly. T-cell tumors and T-cell lines contained a higher number of MT molecules (70,000-125,000 molecules/cell) compared to normal T-lymphocytes. The sensitivities of various lymphoid cells to the DNA methylating agent N-methyl-N'-nitro-N-nitrosoguanidine correlated well with MT activities observed in cell extracts.
mesh_terms: D002454:Cell Differentiation; D002470:Cell Survival / Q000187:drug effects; D004260:DNA Repair; D006801:Humans; D066298:In Vitro Techniques; D007945:Leukemia, Lymphoid / Q000201:enzymology; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology*; D008780:Methyltransferases / Q000032:analysis*; D019853:O(6)-Methylguanine-DNA Methyltransferase; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*
chemical_list: D008769:Methylnitronitrosoguanidine; D008780:Methyltransferases; D019853:O(6)-Methylguanine-DNA Methyltransferase