Molecular Chaperones in the Cytosol: from Nascent Chain to Folded Protein
F. Ulrich Hartl,
Manajit Hayer-Hartl
Efficient folding of many newly synthesized proteins depends on
assistance from molecular chaperones, which serve to prevent protein misfolding and aggregation in the crowded environment of the
cell. Nascent chain-binding chaperones, including trigger factor,
Hsp70, and prefoldin, stabilize elongating chains on ribosomes in a
nonaggregated state. Folding in the cytosol is achieved either on
controlled chain release from these factors or after transfer of newly
synthesized proteins to downstream chaperones, such as the chaperonins.
These are large, cylindrical complexes that provide a central
compartment for a single protein chain to fold unimpaired by
aggregation. Understanding how the thousands of different proteins synthesized in a cell use this chaperone machinery has profound implications for biotechnology and medicine.
Department of Cellular Biochemistry, Max-Planck-Institut
für Biochemie, Am Klopferspitz 18A, D-82152 Martinsried, Germany.
*To whom correspondence should be addressed. E-mail:
uhartl{at}biochem.mpg.de
