Protein disulfide isomerases (PDIs), a family of thiol-disulfide oxidoreductases that are ubiquitous in
all eukaryotes, are the principal catalysts for disulfide bond formation. Here, we investigated three
rice (Oryza sativa) PDI family members (PDIL1;1, PDIL1;4, and PDIL2;3) and found that PDIL1;1
exhibited the highest catalytic activity for both disulfide bond formation and disulfide bond reduction.
The activity of PDIL1;1-catalyzed disulfide bond reduction, in which two redox-active sites
were involved, was enhanced by increasing the glutathione concentration. These results suggest
that PDIL1;1 plays primary roles in both disulfide bond formation and disulfide bond reduction,
which allow for redox control of protein quality and packaging.