Figure 8.

Accelerated turnover of Rho proteins in Icmt-deficient fibroblasts. (a) K-Ras-Icmt^flx/flx and K-Ras-Icmt^Δ/Δ fibroblasts were labeled with [³⁵S]methionine/cysteine for 2 hours and then incubated in regular medium supplemented with 4 mM “cold” methionine and cysteine for the indicated times. Rho proteins were immunoprecipitated from total cell extracts with a pan-Rho antibody, resolved by SDS-PAGE, and then visualized by autoradiography as described in the Methods section. (b) Pulse-chase analysis of Rho protein disappearance in K-Ras-Icmt^flx/flx and the derivative K-Ras-Icmt^Δ/Δ fibroblasts. Graphs show mean densitometry results from three independent experiments. (c) Pulse-chase analysis of Ras proteins in K-Ras-Icmt^flx/flx and the derivative K-Ras-Icmt^Δ/Δ fibroblasts. Ras proteins were immunoprecipitated from total cell extracts with a pan-Ras antibody, resolved by SDS-PAGE, and then visualized by autoradiography. Graphs show mean densitometry data from two independent experiments.