Defining the protein–protein interactions of the mammalian endoplasmic reticulum oxidoreductases (EROs)

The ER (endoplasmic reticulum) is the site of protein folding for all eukaryotic secreted and plasma membrane proteins. Disulphide bonds are formed in many of these proteins through a dithiol–disulphide exchange chain comprising two types of protein catalysts: PDI (protein disulphide-isomerase) and ERO (ER oxidoreductase) proteins. This review will examine what we know about ERO function, and will then consider ERO interactions and their implications for mammalian oxidative protein folding.