HSP70 CHAPERONE SYSTEMS - DIVERSITY OF CELLULAR FUNCTIONS AND MECHANISM OF ACTION

Hsp70 chaperone systems play an essential role in the life cycle of ma ny proteins not only in an hostile environment but also under normal g rowth conditions. In the course of evolution the diversification of fu nctions was accompanied by an amplification of components of the Hsp70 system. Here strategies are reviewed how different Hsp70 systems work independently or cooperate with each other in a functional network to perform their housekeeping tasks even under stress conditions. We fur ther discuss how co-chaperones which act as targeting factors regulate the cycle of substrate binding and release upon which the Hsp70 chape rone activity depends.