The effect of MG132 and virus infection on cellular protein synthesis.

<p>(A) Protein extracts were purified from control HeLa cells, cells infected with VSV for 4 h, cells treated with 5 µM of MG132 for 4 h, and cells infected with VSV and treated with MG132 for 4 h. All cells were incubated with S³⁵ methionine/cysteine for last 30 min before the protein extracts purification. Cytoplasmic protein extracts were analyzed by electrophoresis and autoradiography. (B) Cytoplasmic protein extracts from control, VSV infected, and MG treated cells were precipitated with anti-actin Abs, and the complexes were purified on protein A agarose. S³⁵ labeled actin was analyzed by electrophoresis and autoradiography. (C) Cytoplasmic S³⁵-labeled protein extracts from MG-treated and poliovirus-infected cells were precipitated with anti-actin Abs and analyzed as described in panel B. All protein bands' intensity was detected by ImageJ software to calculate percentage of protein synthesis inhibition.