Oxidative protein folding and unfolded protein response elicit differing redox regulation in endoplasmic reticulum and cytosol of yeast

► Induction of the UPR causes reduction of ER and cytosol. ► Oxidative protein folding does not affect ER redox state, but reduces the cytosol. ► Pdi1 and glutathione peroxidase cause ER oxidation and reduction of the cytosol. ► Redox processes in the ER are counterbalanced by cross talk with the cytosol. ► This study can serve as model for disease related ER stress in higher eukaryotes.