XBP1

This gene encodes a transcription factor that regulates MHC class II genes by binding to a promoter element referred to as an X box. This gene product is a bZIP protein, which was also identified as a cellular transcription factor that binds to an enhancer in the promoter of the T cell leukemia virus type 1 promoter. It may increase expression of viral proteins by acting as the DNA binding partner of a viral transactivator. It has been found that upon accumulation of unfolded proteins in the endoplasmic reticulum (ER), the mRNA of this gene is processed to an active form by an unconventional splicing mechanism that is mediated by the endonuclease inositol-requiring enzyme 1 (IRE1). The resulting loss of 26 nt from the spliced mRNA causes a frame-shift and an isoform XBP1(S), which is the functionally active transcription factor. The isoform encoded by the unspliced mRNA, XBP1(U), is constitutively expressed, and thought to function as a negative feedback regulator of XBP1(S), which shuts off transcription of target genes during the recovery phase of ER stress. A pseudogene of XBP1 has been identified and localized to chromosome 5. [provided by RefSeq, Jul 2008]

Description

X-box binding protein 1

Tissue specificity

Tissue enhanced (pancreas)

Predicted location

Intracellular, Membrane

Protein family

Cancer-related genes
Disease related genes
Mapped to neXtProt
Mapped to UniProt SWISS-PROT
Predicted intracellular proteins
Predicted membrane proteins
Protein evidence (Ezkurdia et al 2014)
Transcription factors

Chromosome

22 (28794555 - 28800597)

Ensembl ID

ENSG00000100219  (ver. 103.38)

Orthologs

Mouse Xbp1: ENSMUSG00000020484

UniProt

P17861

neXtProt

NX_P17861

Human splice variants
Mouse splice variants

Protein structure