Cystosolic chaperonin subunits have a conserved ATPase domain but diverged polypeptide-binding domains.
CCT (also called the TCP-1 complex or TriC) is a chaperonin found in the eukaryotic cytosol, and has unique structural and functional features. Unlike homo-oligomeric chaperonins, CCT comprises at least eight different subunits, and appears to have a limited range of physiological substrates. We have analysed CCT sequences in light of the recent determination of the crystal structure and mutational identification of the functional domains of the bacterial chaperonin GroEL. A high level of identity among all chaperonin subunits is observed in those regions that correspond to the ATP-binding site of GroEL. By contrast, no significant identity is shared in the region corresponding to the polypeptide-binding region of GroEL, either between CCT subunits or between CCT subunits and GroEL. This suggests that the polypeptide-binding sites of CCT subunits have diverged both from each other and from GroEL, which may explain the apparently different range of substrates recognized by CCT.
Kim
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Department of Genetics, Yale University School of Medicine, Boyer Center, Newhaven, CT 06510.
Willison
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KR
Horwich
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AL
D000251:Adenosine Triphosphatases / Q000737:chemistry*; D000595:Amino Acid Sequence; D001665:Binding Sites; D005075:Biological Evolution; D018834:Chaperonin 60 / Q000737:chemistry; D018833:Chaperonins / Q000737:chemistry*; D017124:Conserved Sequence; D047908:Intracellular Signaling Peptides and Proteins; D008869:Microtubule-Associated Proteins; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry* / Q000502:physiology; D010455:Peptides / Q000378:metabolism*; D016415:Sequence Alignment; D044767:Ubiquitin-Protein Ligases; D056427:t-Complex Genome Region
D018834:Chaperonin 60; D047908:Intracellular Signaling Peptides and Proteins; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins; D010455:Peptides; C116196:PPP1R11 protein, human; D044767:Ubiquitin-Protein Ligases; D000251:Adenosine Triphosphatases; D018833:Chaperonins