XBP1: Lysates

X-box binding protein 1 (XBP1; also tax-responsive element-binding protein 5 (TREB5) is a ubiquitously expressed member of the bZIP family of proteins. The spliced form of XPB1 (XBP1S) is a 376 amino acid (aa), 55 kDa transcription factor essential for the unfolded protein response. XBP1S is formed during endoplasmic reticulum stress by IRE-1-mediated splicing that creates a 210 aa substitution for XBP1 aa 161 - 261.