Enables DNA-binding transcription factor activity and sequence-specific DNA binding activity. Involved in several processes, including endoplasmic reticulum unfolded protein response; negative regulation of endoplasmic reticulum stress-induced intrinsic apoptotic signaling pathway; and serotonin secretion, neurotransmission. Located in cytoplasm and nucleus. Biomarker of borna disease. Orthologous to human XBP1 (X-box binding protein 1). [provided by Alliance of Genome Resources, Apr 2022]