Effect of temperature (A and B), and oxidative stress (B) in complex I assembly intermediates. Indicated strains were grown at 26°C for 16 h followed by 3-h incubation either at 26°C or at 37°C in the presence of 1 mg/ml cycloheximide (CHM), 1 mM KCN, 10 mM N-acetylcysteine (NAC), 10 mM H2O2 (H2O2), or 10 mM H2O2 plus cycloheximide (CHM+H2O2). Mitochondrial extracts were analyzed by Western blotting with antibodies against the 13.4L protein, the complex I subunit 21.3c kDa, and the COREII complex III subunit.