Recombinant human IRE1 (protein kinase inositol-requiring enzyme 1), also known as serine/threonine-protein kinase/endoribonuclease 1, encompassing amino acids 649-977. This construct contains an N-terminal His-tag (10xHis) followed by an Avi-Tag™. The His-tag and the Avi-Tag™ are separated by an optimal TEV (tobacco etch virus) protease target sequence that allows cleavage of the His-tag and release of the Avi-IRE1 recombinant (TEV: tobacco etch virus cysteine protease #50308). The protein was affinity purified.