Uracil-DNA glycosylase and deoxyuridine triphosphatase: studies of activity and subcellular location in human normal and malignant lymphocytes.

Crude extracts of human lymphocytic cells contain two enzymes which putatively exclude uracil from DNA: uracil-DNA glycosylase and deoxyuridine triphosphatase (dUTPase). Their activities were found in different types of benign and malignant cells: resting and mitogen-stimulated peripheral blood T- and B-lymphocytes, as well as in a lymphoblastic cell line with neither B- or T-differentiation. The proliferative stage of the cell determined the dUTPase activity rather than the phenotypic origin of the population. This was demonstrated with peripheral blood lymphocytes: the activity of dUTPase in resting cells was very low and a 15- to 27-fold increase took place during mitogenic stimulation. Mitogens slightly enhanced the uracil-DNA glycosylase activity. The physiological roles of these enzymes may be connected with their subcellular location. The subcellular distributions of the enzymes were different; uracil-DNA glycosylase was most abundantly present near to cellular DNA, i.e., in nuclei, but dUTPase was nearly exclusively a cytoplasmic enzyme.