Molecular chaperones in the cytosol: from nascent chain to folded protein.
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.
Hartl
F Ulrich
FU
Department of Cellular Biochemistry, Max-Planck-Institut für Biochemie, Am Klopferspitz 18A, D-82152 Martinsried, Germany. uhartl@biochem.mpg.de
Hayer-Hartl
Manajit
M
D018833:Chaperonins / Q000737:chemistry / Q000378:metabolism; D003600:Cytosol / Q000737:chemistry*; D005057:Eukaryotic Cells / Q000737:chemistry* / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism; D046911:Macromolecular Substances; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry / Q000378:metabolism*; D011387:Prokaryotic Cells / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D014176:Protein Biosynthesis; D011487:Protein Conformation; D017510:Protein Folding; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism
D018840:HSP70 Heat-Shock Proteins; D046911:Macromolecular Substances; D018832:Molecular Chaperones; D011506:Proteins; C112806:prefoldin; D018833:Chaperonins