Chapter 23 Assaying Proteins for Molecular Chaperone Activity

Abstract

Publisher Summary This chapter discusses the assaying proteins for molecular chaperone activity. Molecular chaperones play critical roles in protein folding, assembly, and translocation. Additionally, molecular chaperones maintain other proteins in translocationally competent, unfolded conformations and also function during subsequent folding. Recent evidence has suggested that molecular chaperones are probably the cellular factors responsible for this discrepancy. The cellular requirement for chaperones is because of the adverse conditions that can exist in cells that jeopardize productive protein folding. These conditions include the high cellular concentration of folding intermediates that are prone to aggregation or misfolding or that can result from the presence of environmental stresses—such as heat shock—which promote protein unfolding. Several properties define molecular chaperone activity: (1) the ability to recognize and bind unfolded proteins, (2) to suppress aggregation during protein unfolding and folding, (3) to influence the yield of folding, and (4) to carry out properties 2 and 3 at approximately stoichiometric levels.