Terminal deoxynucleotidyltransferase containing megadalton complex from young rat thymus nuclei: identification and characterization.

Nuclear matrix prepared from 2-3 week old rat thymuses contains tightly bound TdT activity which has been quantitatively solubilized with nonionic detergent and sonication. TdT is contained in a discrete complex with a sedimentation value of 23 S. The complex is retained on an anti-TdT antibody column and contains DNA ligase and 3'-5' exonuclease activities as well as DNA and several other proteins but is devoid of replicative DNA polymerases. Such a type of multienzyme complex is absent from the nuclear extracts of thymus prepared from older rats and also from liver and spleen extracts of young and old rats.