Format

Send to:

Choose Destination
See comment in PubMed Commons below
Curr Biol. 1994 Feb 1;4(2):89-99.

Identification of six Tcp-1-related genes encoding divergent subunits of the TCP-1-containing chaperonin.

Author information

  • 1Institute of Cancer Research, Chester Beatty Laboratories, London, UK.

Abstract

BACKGROUND:

TCP-1 is a 60 kD subunit of a cytosolic hetero-oligomeric chaperone that is known to be involved in the folding of actin and tubulin. This protein is a member of the chaperonin family, which includes Escherichia coli GroEL, the mitochondrial heat-shock protein Hsp60, the plastid Rubisco-subunit-binding protein and the archaebacterial protein TF55. These chaperonins assist the folding of proteins upon ATP hydrolysis.

RESULTS:

Using two-dimensional gel analysis, we have identified nine different subunits of TCP-1-containing chaperonin complexes from mammalian testis and seven different subunits of such complexes from mouse F9 cells. We have isolated full-length mouse cDNAs encoding six novel TCP-1-related polypeptides and show that these cDNAs encode subunits of the TCP-1-containing cytosolic chaperonin. These subunits are between 531 and 545 residues in length. Their sequences are 25-36% identical to one another, 27-35% identical to that of TCP-1 and 32-39% identical to that of the archaebacterial chaperonin, TF55. We have named these genes, Cctb, Cctg, Cctd, Ccte, Cctz and Ccth, which encode the CCT beta, CCT gamma, CCT delta, CCT epsilon, CCT zeta and CCT eta subunits, respectively, of the 'Chaperonin Containing TCP-1' (CCT). All the CCT subunits contain motifs that are also shared by all other known chaperonins of prokaryotes and eukaryotic organelles, and that probably relate to their common ATPase function.

CONCLUSION:

It is likely that each CCT subunit has a specific, independent function, as they are highly diverged from each other but conserved from mammals to yeast. We suggest that the expansion in the number of types of CCT subunit, compared with other chaperonins, has allowed CCT to carry out the more complex functions that are required for the folding and assembly of highly evolved eukaryotic proteins.

PMID:
7953530
[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science
    Loading ...
    Write to the Help Desk