X-box-binding protein 1; XBP-1; Tax-responsive element-binding protein 5 (XBP1, TREB5, XBP2)

Function

• transcription factor essential for
  • hepatocyte growth
  • differentiation of plasma cells
  • immunoglobulin secretion
  • unfolded protein response
• acts during endoplasmic reticulum stress (ER) by activating unfolded protein response target genes via direct binding to the UPR element (UPRE)
• binds DNA preferably to the CRE-like element 5'-GATGACGTG[TG]N(3)[AT]T-3', & also to some TPA response elements (TRE)
• binds to the HLA DR-alpha promoter
• binds to the Tax-responsive element of HTLV-I
• potent transcriptional activator
• induced by ERN1 in response to an ER stress, which cleaves a 26-bp fragment inducing a frameshift of the mRNA transcript

Structure

• belongs to the bZIP family
• contains 1 bZIP domain

Compartment

nucleus

Alternative splicing

named isoforms=2

Expression

• up-regulated by ATF6 via direct binding to the ERSE in response to endoplasmic reticulum stress

More general terms

• basic leucine zipper (bZIP) family protein

Database

• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:7494
• OMIM: https://mirror.omim.org/entry/194355
• UniProt: http://www.uniprot.org/uniprot/P17861.html