PROSITE documentation PDOC00610
Chaperonins TCP-1 signatures


The TCP-1 protein [1,2] (Tailless Complex Polypeptide 1) was first identified in mice where it is especially abundant in testis but present in all cell types. It has since been found and characterized in many other mammalian species, in Drosophila and in yeast. TCP-1 is a highly conserved protein of about 60 Kd (556 to 560 residues) which participates in a hetero-oligomeric 900 Kd double-torus shaped particle [3] with 6 to 8 other different subunits. These subunits, the chaperonin containing TCP-1 (CCT) subunit β, γ, delta, epsilon, zeta and eta are evolutionary related to TCP-1 itself [4,5]. The CCT is known to act as a molecular chaperone for tubulin, actin and probably some other proteins.

The CCT subunits are highly related to archebacterial counterparts:

  • TF55 and TF56 [6], a molecular chaperone from Sulfolobus shibatae. TF55 has ATPase activity, is known to bind unfolded polypeptides and forms a oligomeric complex of two stacked nine-membered rings.
  • Thermosome [7], from Thermoplasma acidophilum. The thermosome is composed of two subunits (α and β) and also seems to be a chaperone with ATPase activity. It forms an oligomeric complex of eight-membered rings.

The TCP-1 family of proteins are weakly, but significantly [8], related to the cpn60/groEL chaperonin family (see <PDOC00268>).

As signature patterns of this family of chaperonins, we chose three conserved regions located in the N-terminal domain.

Expert(s) to contact by email:

Willison K.R.

Last update:

December 2004 / Pattern and text revised.


Technical section

PROSITE methods (with tools and information) covered by this documentation:

TCP1_1, PS00750; Chaperonins TCP-1 signature 1  (PATTERN)

TCP1_2, PS00751; Chaperonins TCP-1 signature 2  (PATTERN)

TCP1_3, PS00995; Chaperonins TCP-1 signature 3  (PATTERN)


1AuthorsEllis J.
TitleProtein folding. Cytosolic chaperonin confirmed.
SourceNature 358:191-191(1992).
PubMed ID1352857

2AuthorsNelson R.J. Craig E.A.
TitleTCP1 - molecular chaperonin of the cytoplasm?
SourceCurr. Biol. 2:487-489(1992).
PubMed ID15335898

3AuthorsLewis V.A. Hynes G.M. Zheng D. Saibil H. Willison K.R.
TitleT-complex polypeptide-1 is a subunit of a heteromeric particle in the eukaryotic cytosol.
SourceNature 358:249-252(1992).
PubMed ID1630492

4AuthorsKubota H. Hynes G. Carne A. Ashworth A. Willison K.R.
TitleIdentification of six Tcp-1-related genes encoding divergent subunits of the TCP-1-containing chaperonin.
SourceCurr. Biol. 4:89-99(1994).
PubMed ID7953530

5AuthorsKim S. Willison K.R. Horwich A.L.
TitleCystosolic chaperonin subunits have a conserved ATPase domain but diverged polypeptide-binding domains.
SourceTrends Biochem. Sci. 19:543-548(1994).
PubMed ID7846767

6AuthorsTrent J.D. Nimmesgern E. Wall J.S. Hartl F.U. Horwich A.L.
TitleA molecular chaperone from a thermophilic archaebacterium is related to the eukaryotic protein t-complex polypeptide-1.
SourceNature 354:490-493(1991).
PubMed ID1836250

7AuthorsWaldmann T. Lupas A. Kellermann J. Peters J. Baumeister W.
TitlePrimary structure of the thermosome from Thermoplasma acidophilum.
SourceBiol. Chem. Hoppe-Seyler 376:119-126(1995).
PubMed ID7794526

8AuthorsHemmingsen S.M.
TitleWhat is a chaperonin?
SourceNature 357:650-650(1992).
PubMed ID1352040

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