ABSTRACT
It has been known for more than a decade that eucaryotes have multiple families of genes encoding molecular chaperones, particularly those of the Hsp70 and DnaJ classes. The completion of the sequence of the S. cerevisiae genome allows a unique opportunity to consider the entire array of molecular chaperones within a eucaryotic organism. Although some of the predicted proteins are yet to be analyzed, a great deal of useful information has been obtained for many members. Different, but related proteins are found in various cellular compartments: the cytosol/nucleus, ER and mitochondria. Each of these three cellular compartments has more than one type of Hsp70, while the ER and the cytosol have more than one DnaJ. The presence of multiple chaperones of both the Hsp70 and DnaJ classes raises the question of whether related proteins in the same compartment are functionally different. In addition, it will be important to dissect the interrelationship between the Hsp70s and proteins with which they interact, such as DnaJs, in order to understand the roles of chaperones in cellular processes. Below we outline the families of molecular chaperones and their functions within the cell as we understand them today, focusing on those of the Hsp70 class and the proteins that function with them.
