Figure 5.

Impaired postreplication repair of human cells transformed with mutant hRAD18. (A) Cells (Mori-SV C28F or Mori-SV Vec) were irradiated with UV (8 J/m²), incubated for 30 min, and then pulse labeled with [³H]thymidine (0.93 MBq/ml) for 30 min. Samples were sedimented on 5–20% alkaline sucrose gradients from right to left, and the profile of UV-irradiated cell sample (●) was compared with that of the nonirradiated control cell sample (○). (Left) Mori-SV-stable transformant with vector alone. (Right) Mori-SV-stable transformant with hRAD18(C28F). (B) After the pulse label, cells were chased for 90 min in fresh medium containing 10 μM unlabeled thymidine. Samples were analyzed by the same method used in A. Closed and open arrowheads indicate the positions of bacteriophage λ DNA (42 kb) and bacterial artificial chromosome DNA (100 kb), respectively.