(A) Wild-type (WT), Gal-GRX4, grx3Δ (strain background W303-1A), and grx3/4Δ (strain background BY4742) were grown in SD medium for 40 h. Tenfold serial dilutions were spotted onto YPEG plates and incubated for 2 days at 30°C. (B) WT, Gal-GRX4 and Gal-SSQ1 strains harbouring plasmid pFET3-GFP were grown in SD minimal medium. At the indicated times, FET3 promoter activities were determined by measuring the GFP-specific fluorescence emission of cells, and cell extracts were assayed for aconitase and catalase activities, or (C) analyzed for the indicated proteins by immunostaining. (D) Enzyme activities of respiratory complexes II (SDH) and IV (COX) were determined relative to malate dehydrogenase (MDH) in mitochondria isolated from Gal-GRX4 cells cultivated in rich glucose medium for 40 h and 64 h, and from Gal-GRX4 cells expressing GRX4 from vector pCM189 (+Grx4). Error bars indicate the SEM (n ≥ 4).