X-box binding protein 1 (XBP-1) is a basic-region, leucine zipper type transcription factor that belongs to the CREB/ATF family and mediates one of the three arms of unfolded protein response (UPR) adaptation to endoplasmic reticulum (ER) stressors. The accumulation of unfolded or misfolded proteins in the ER is a threat to cell survival and results in a condition known as ER-stress. To overcome this stress, the ER initiates specific signaling pathways encompassed by the ER stress response. Among these are translational attenuation, upregulation of ER chaperone proteins and proteins that facilitate folding, activation of NFkB signaling, and, as a last resort, the induction of apoptosis. Under basal conditions, XBP-1 is ubiquitously expressed as a 33 kDa XBP-1u isoform. The initiation of ER stress activates the endonuclease activity of the transmembrane kinase and endoribonuclease inositol-requiring enzyme-1 (IRE-1) in an unconventional cleavage and re-ligation reaction producing an active 52 kDa splice-variant form of XBP-1 known as XBP-1s. XBP-1s transcriptionally regulates the production of additional ER chaperones and secretory proteins to maintain the function of the organelle and the health of the cell. XBP-1 is involved in the response of many diseases linked to ER stress (ischemia, neurodegeneration, cancer, diabetes), which makes this an attractive marker for many therapeutic areas.


XBP-1 Singleplex Products

Our XBP-1 immunoassays provide fast, accurate, reproducible, and highly sensitive measurements of XBP-1. MSD’s MULTI-ARRAY technology uses simple protocols, requires minimal sample, and quantifies analyte concentration over a wide dynamic range.


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