Enables protein-disulfide reductase activity. Involved in negative regulation of IRE1-mediated unfolded protein response. Part of endoplasmic reticulum chaperone complex. Is expressed in embryo; liver; lung epithelium; and pancreas epithelium. Orthologous to human PDIA6 (protein disulfide isomerase family A member 6). [provided by Alliance of Genome Resources, Apr 2022]