CELL STRESS PROTEINS ( PROTEIN REVIEWS, VOLUME 7)

Stressproteinssuchastheheatshockproteins(Hsp)andglucose-regulatedproteins (Grp) are front-line molecules in responses to cellular insult and play key roles in the viability of single cell organisms exposed to environmental stresses. However, the discovery of the roles of Hsp and Grp as molecular chaperones indicates much wider functions in the physiology of cells and organisms. It is now clear that some stress proteins are expressed constitutively and are key mediators of housekeeping protein folding in the day-to-day existence of the cell.The maturation of enzymes,transcriptionfactors,andcellsurfacereceptorsreliesonthesefunctionsofthestress proteins. In addition, the ability of stress proteins to manipulate the structures of target proteins has lent them cell regulatory properties over and above their role in folding the proteome and they play key roles in controlling signal transduction, cell death pathways and transcription.