InterPro domain: IPR017998

Protein folding is thought to be the sole result of properties inherent in polypeptide primary sequences. Sometimes, however, additional proteins are required to mediate correct folding and subsequent oligomer assembly [ 1 ]. These `helpers', or chaperones, bind to specific protein surfaces, preventing incorrect folding and formation of non-functional structures [ 2 ].

The tailless complex polypeptide 1 (TCP-1) is a highly structurally conserved molecular chaperone located in the cytosol [ 3 ]. The protein has also been shown to bind to Golgi membranes and to microtubules, this latter property suggesting a role in mitotic spindle formation in dividing cells (especially in sperm, where it is highly abundant) [ 4 ]. TCP-1 forms a double ring structure, similar to the 10kDa and 60kDa chaperonins, with 6-8 subunits per ring. The amino acid sequence is significantly similar to the 60kDa chaperonin, and to TF55, a chaperone from the archaebacterium Sulfolobus shibatae [ 5 ].

1. Homologous plant and bacterial proteins chaperone oligomeric protein assembly. Nature 333, 330-4
2. Cloning of a cDNA encoding the Tcp-1 (t complex polypeptide 1) homologue of Arabidopsis thaliana. Gene 122, 381-2
3. Is yeast TCP1 a chaperonin? Nature 356, 392
4. A molecular chaperone from a thermophilic archaebacterium is related to the eukaryotic protein t-complex polypeptide-1. Nature 354, 490-3