Function in protein folding of TRiC, a cytosolic ring complex containing TCP-1 and structurally related subunits.
T-complex polypeptide 1 (TCP-1) was analyzed as a potential chaperonin (GroEL/Hsp60) equivalent of the eukaryotic cytosol. We found TCP-1 to be part of a hetero-oligomeric 970 kDa complex containing several structurally related subunits of 52-65 kDa. These members of a new protein family are assembled into a TCP-1 ring complex (TRiC) which resembles the GroEL double ring. The main function of TRiC appears to be in chaperoning monomeric protein folding: TRiC binds unfolded polypeptides, thereby preventing their aggregation, and mediates the ATP-dependent renaturation of unfolded firefly luciferase and tubulin. At least in vitro, TRiC appears to function independently of a small co-chaperonin protein such as GroES. Folding of luciferase is mediated by TRiC but not by GroEL/ES. This suggests that the range of substrate proteins interacting productively with TRiC may differ from that of GroEL. We propose that TRiC mediates the folding of cytosolic proteins by a mechanism distinct from that of the chaperonins in specific aspects.
Program in Cellular Biochemistry and Biophysics, Rockefeller Research Laboratories, Sloan-Kettering Institute, New York, NY 10021.
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Frydman
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Nimmesgern
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Erdjument-Bromage
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Wall
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Tempst
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Hartl
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry; D002417:Cattle; D018834:Chaperonin 60; D018833:Chaperonins; D001517:Coleoptera / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D006360:Heat-Shock Proteins / Q000737:chemistry; D047908:Intracellular Signaling Peptides and Proteins; D008156:Luciferases / Q000737:chemistry / Q000378:metabolism; D008297:Male; D017348:Microscopy, Electron, Scanning Transmission; D008869:Microtubule-Associated Proteins; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D011506:Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D014404:Tubulin / Q000737:chemistry; D044767:Ubiquitin-Protein Ligases; D056427:t-Complex Genome Region
D001426:Bacterial Proteins; D018834:Chaperonin 60; D006360:Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins; D011506:Proteins; D014404:Tubulin; D000255:Adenosine Triphosphate; D008156:Luciferases; C116196:PPP1R11 protein, human; D044767:Ubiquitin-Protein Ligases; D000251:Adenosine Triphosphatases; D018833:Chaperonins