An enzyme activity in normal and ataxia telangiectasia cell lines which is involved in the repair of γ-irradiation-induced DNA damage

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Abstract
An enzyme enhancing the activity of DNA polymerase I (EC 2.7.7.7) for .gamma.-irradiated calf thymus DNA was demonstrated in cellular extracts of normal human fibroblasts and lymphoid-cell lines. This enzyme was deficient in all cellular extracts of fibroblasts and lymphoid-cell lines examined from patients with the autosomal recessive disease ataxia telangiectasia. The activity in cellular extracts from normal fibroblasts was removed when heated to 100.degree. C for 2 min, or when the assay was performed at 4.degree. C. No significant deficiency in primer-activating enzyme activity was observed in cell-free extracts of lymphoid lines from patients with xeroderma pigmentosum, Huntington''s chorea or neurofibromatosis, or from an ataxia telangiectasia heterozygote.