Oxidative Stress Posttranslationally Regulates the Expression of Ha-Ras and Ki-Ras in Cultured Astrocytes
Figure 2
Expression of GTP-bound Ha-Ras and Ki-Ras in cultured astrocytes exposed to hydrogen peroxide. Total active GTP-bound Ras was collected on Raf1-RBD beads and probed with Ha-Ras or Ki-Ras antibodies on the same membrane. Note in (a) that a 21 kDa band of GTP-bound Ha-Ras appeared after 5 min of exposure to hydrogen peroxide and disappeared afterwards. The immunoblot in (a) shows the putative activated form of Ki-Ras, which is present as a faint band at 25 kDa in control cultures, and slightly increased at 5 min after hydrogen peroxide. This band might correspond to a GTP-bound farnesylated form of Ki-Ras because it was present in HEK-293 cells expressing Val-12 Ki-Ras, but not in cells expressing a Ki-Ras mutant (Val-12/Ala-185), which cannot be farnesylated (b). All immunoblots were repeated twice with similar results.
