ABSTRACT
The major stress defense systems as more or less independent systems, each responsible for its specific tasks. This chapter demonstrates that these systems form one integrated cellular defense system against the different insults by various environmental stressors. Proteotoxic stress and the stress-protein systems are characterized by stressors causing denaturation of proteins and the defense system responding by induction of stress proteins. Oxidative stress is caused by oxygen free radicals generated by components of the oxidative stress response system during the processing of oxidants. The stress-protein system reacts to disturbances of structural integrity and damage of proteins and enzymes, irrespective of the type of stressor. Oxidative stressors oxidize thiols, which affect the cellular redox state if consumed glutathione is not replenished fast enough. The intricate network of cellular stress defense mechanisms contributes to homeostasis, not only at the cellular level, but also at the level of the whole organism.
