MOLECULAR CHAPERONES IN PROTEIN-FOLDING - THE ART OF AVOIDING STICKY SITUATIONS

In the cell, as in vitro, the final conformation of a protein is determined by its amino acid sequence. But whereas some isolated proteins can be denatured and refolded in vitro in the absence of other macromolecular cellular components, folding and assembly of polypeptides in vivo involves other proteins, many of which belong to families that have been highly conserved during evolution. These proteins, known as 'molecular chaperones', are thought to temporarily stabilize unfolded or partially folded structures and to maintain them in a state competent for subsequent folding and assembly. Over the next few months, TIBS will publish a series of articles that will highlight the role of molecular chaperones in protein synthesis, membrane translocation and folding. The series begins this month with an article on the Hsp70 and Hsp60 families of proteins by Franz-Ulrich Hartl, Roman Hlodan and Thomas Langer. Further topics to be covered include: the role of Hsp70 in protein import into mitochondria; substrate-binding specificities of Hsp70; DnaJ; small Hsps and Hsp90; PDI; p88 (calnexin); and GroE and TCP-1 chaperones. It is hoped that the articles in the series can be read individually, or collectively, depending on the interest of the reader. We hope that our readers will find the series both useful and enjoyable.