Summary: Prefoldin subunit
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This family comprises of several prefoldin subunits. The biogenesis of the cytoskeletal proteins actin and tubulin involves interaction of nascent chains of each of the two proteins with the oligomeric protein prefoldin (PFD) and their subsequent transfer to the cytosolic chaperonin CCT (chaperonin containing TCP-1). Electron microscopy shows that eukaryotic PFD, which has a similar structure to its archaeal counterpart, interacts with unfolded actin along the tips of its projecting arms. In its PFD-bound state, actin seems to acquire a conformation similar to that adopted when it is bound to CCT .
Martin-Benito J, Boskovic J, Gomez-Puertas P, Carrascosa JL, Simons CT, Lewis SA, Bartolini F, Cowan NJ, Valpuesta JM; , EMBO J 2002;21:6377-6386.: Structure of eukaryotic prefoldin and of its complexes with unfolded actin and the cytosolic chaperonin CCT. PUBMED:12456645 EPMC:12456645
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR004127
This entry comprises of several prefoldin subunits. Prefoldin (PFD) is a chaperone that interacts exclusively with type II chaperonins, hetero-oligomers lacking an obligate co-chaperonin that are found only in eukaryotes (chaperonin-containing T-complex polypeptide-1 (CCT)) and archaea. Eukaryotic PFD is a multi-subunit complex containing six polypeptides in the molecular mass range of 14-23 kDa. In archaea, on the other hand, PFD is composed of two types of subunits, two alpha and four beta. The six subunits associate to form two back-to-back up-and-down eight-stranded barrels, from which hang six coiled coils. Each subunit contributes one (beta subunits) or two (alpha subunits) beta hairpin turns to the barrels. The coiled coils are formed by the N and C termini of an individual subunit. Overall, this unique arrangement resembles a jellyfish. The eukaryotic PFD hexamer is composed of six different subunits; however, these can be grouped into two alpha-like (PFD3 and -5) and four beta-like (PFD1, -2, -4, and -6) subunits based on amino acid sequence similarity with their archaeal counterparts. Eukaryotic PFD has a six-legged structure similar to that seen in the archaeal homologue [PUBMED:11106732, PUBMED:12456645]. This family contains the archaeal alpha subunit, eukaryotic prefoldin subunits 3 and 5 and the UXT (ubiquitously expressed transcript) family.
Eukaryotic PFD has been shown to bind both actin and tubulin co-translationally. The chaperone then delivers the target protein to CCT, interacting with the chaperonin through the tips of the coiled coils. No authentic target proteins of any archaeal PFD have been identified, to date.
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Cellular component||prefoldin complex (GO:0016272)|
|Molecular function||unfolded protein binding (GO:0051082)|
|Biological process||protein folding (GO:0006457)|
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The Prefoldin domain forms a coiled-coil structure that is involved in substrate-binding in the the chaperone co-factor prefoldin (PFD). Each PFD is assembled from two alpha and four beta subunits. Each alpha subunit contains two, and each beta subunit one, central beta-hairpin that is flanked N- and C-terminally by coiled-coil helices. The N-terminal regions, the prefoldin domain, are found facing into the central cavity of the chaperone. Here exposed hydrophobic patches form an interaction with the substrate (an unfolded protein) .
The clan contains the following 3 members:Prefoldin Prefoldin_2 Prefoldin_3
We make a range of alignments for each Pfam-A family:
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Curation and family details
|Seed source:||Pfam-B_1664 (release 6.4)|
|Author:||Bateman A, Moxon SJ|
|Number in seed:||37|
|Number in full:||1254|
|Average length of the domain:||116.60 aa|
|Average identity of full alignment:||19 %|
|Average coverage of the sequence by the domain:||50.84 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||12|
|Download:||download the raw HMM for this family|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Prefoldin domain has been found. There are 2 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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