title: Biosynthesis of mammalian DNA ligase.
abstract: A monospecific antibody against calf thymus DNA ligase composed of a single polypeptide with Mr = 130,000 cross-reacts with rodent and calf thymus DNA ligases. The antibody precipitates a single Mr = 200,000 polypeptide from detergent lysates of [3H] leucine-labeled mouse Ehrlich tumor cells and calf thymocytes. Pulse-chase experiments show that the Mr = 200,000 polypeptide in Ehrlich tumor cells has a half-life of about 0.5 h. In addition to the Mr = 200,000 polypeptide, a Mr = 130,000 polypeptide is detected in the partially purified enzyme preparations from radiolabeled Ehrlich tumor cells. These results suggest that DNA ligase is synthesized in mammalian cells as a Mr = 200,000 polypeptide and that the Mr = 200,000 polypeptide is degraded to a Mr = 130,000 polypeptide by a limited proteolysis in vitro.
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000201:enzymology; D002417:Cattle; D011088:DNA Ligases / Q000096:biosynthesis* / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D005470:Fluorometry; D006207:Half-Life; D008970:Molecular Weight; D011118:Polynucleotide Ligases / Q000096:biosynthesis*; D011817:Rabbits; D013950:Thymus Gland / Q000201:enzymology
chemical_list: D011088:DNA Ligases; D011118:Polynucleotide Ligases