ABSTRACT
The Hsp70 class of molecular chaperones and the related constitutive proteins, the Hsc70s, have a widely diverse set of functions in the cell in addition to their role in the heat shock response (see reviews by Hendrick and Hartl, 1993; Rassow and Pfanner, 1995; Hartl, 1996). The Hsc70s are involved in both the folding of proteins after synthesis on ribosomes and in maintaining proteins in an unfolded state after synthesis (chapter Welch et al.). They are also involved in unfolding proteins prior to translocation through mitochondrial or endoplasmic reticulum membranes, in driving the translocation process itself, and then in refolding these proteins following their translocation through the membranes (chapters Haas and Zimmerman; Dekker and Pfanner).
