Ubiquitously expressed transcript protein UXT is involved in gene transcription regulation. It acts in concert with the corepressor URI1 to regulate androgen receptor transcription (AR). It is an AR N terminus-associated coactivator which may play a role in facilitating receptor-induced transcriptional activation []. It is a protein which interacts with the N terminus of the Down's syndrome candidate region 1 (DSCR1) protein, encoded by a gene located in the human chromosome 21. DSCR1 interacts with calcineurin and is overexpressed in Down's syndrome patients. UXT, which is encoded in human Xp11, is a 157-amino acid protein present in both cytosol and nucleus of the cells []. The members of this family are related to prefoldin, which is part of a molecular chaperone system that promotes the correct folding of nascent polypeptide chains. Prefoldin interacts with the nascent chain to stabilise it prior to its folding within the central cavity of a chaperonin. Prefoldin is a hexamer consisting of two types of subunits, alpha and beta. Archaeal prefoldin contains one type of alpha and one type of beta subunit [], while eukaryotic prefoldin contains two different but related alpha subunits and four related beta subunits [].
This entry represents prefoldin subunit alpha-like proteins. 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 14-23kDa. 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 [, ]. 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.
