Ero1-La is an essential oxidoreductase that oxidizes proteins and is required for the folding of immunoglobulins. Ero-1La covalently binds with PDI (protein disulfide-isomerase) and together they produce disulfide bonds between proteins in the endoplasmic reticulum. Ero1-La and SIRT1 regulate adiponectin secretion from adipose tissue. Ero1-La and associated proteins also modulate PPARg (peroxisome proliferator-activated receptor g) and SIRT1 activities. Ero1-La is stimulated by hypoxia, suggesting that it is regulated through the HIF (hypoxia inducible transcrip-tion factor) pathway. Ero1-La is ubiquitously expressed at low levels but expressed at high levels in upper digestive tract and esophagus. Ero1-La may function both as a monomer and a homodimer.