Subcellular localization and properties of thymidine kinase from adenovirus-infected cells.

The principal cytosol thymidine kinase activity of African green monkey kidney cells increased approximately threefold at 2I to 29 h after infection with adenovirus type 5. Disc polyacrylamide gel electrophoresis (disc PAGE) analyses showed that the electrophoretic mobility relative to the tracking dye (Rm) of the cytosol thymidine kinase from both mock-infected and adenovirus type 5-infected cells was about o'23. The cytosol thymidine kinase from normal cells also resembled the cytosol enzyme from infected cells with respect to phosphate donor specificity and sedimentation coefficient. Mitochondria from normal and virus-infected cells contained a cytosol-like enzyme and, in addition, a distinctive mitochondrial isozyme exhibiting an Rm of about o.6 and a smaller sedimentation coefficient than the cytosol enzyme. The activity of the mitochondrial-specific isozyme of thymidine kinase (Rm = 0-6) was not significantly increased by virus infection. The ratio of the two thymidine kinase activities found in mitochondria also was not markedly changed by virus infection. The results suggest that adenovirus type 5 infection reactivates an inactive molecular form of cytosol thymidine kinase or derepresses the synthesis of the cytosol enzyme, but not that of the mitochondrial-specific thymidine kinase. Adenovirus infection does not alter the electrophoretic mobilities of the cytosol and mitochondrial thymidine kinases.