Description

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.

References
1. J Biol Chem. 2009 May 29;284(22):14904-13. 2. Neoplasia. 2009 May;11(5):436-47. 3. Clin Cancer Res. 2009 Jun 1;15(11):3834-41.

Specification
Aliases	XBP2; TREB5; XBP1
Entrez GeneID	7494
Swissprot	P17861
clone	1C4
WB Predicted band size	28kDa
Host/Isotype	Mouse IgG1
Antibody Type	Primary antibody
Storage	Store at 4°C short term. Aliquot and store at -20°C long term. Avoid freeze/thaw cycles.
Species Reactivity	Human
Immunogen	Purified recombinant fragment of human XBP1 expressed in E. Coli.
Formulation	Ascitic fluid containing 0.03% sodium azide.

Application
ELISA	1/10000