P5-type sulfhydryl oxidoreductase promotes the sorting of proteins to protein body I in rice endosperm cells.

In rice (Oryza sativa) endosperm cells, oxidative protein folding is necessary for the sorting of storage proteins to protein bodies, PB-I and PB-II. Here we examined the role of sulfhydryl oxidoreductase PDIL2;3 (a human P5 ortholog) in the endoplasmic reticulum (ER), using GFP-AB, a PB-I marker in which the N-terminal region (AB) of α-globulin is fused to green fluorescent protein (GFP). RNAi knockdown of PDIL2;3 inhibited the accumulation of GFP-AB in PB-I and promoted its exit from the ER. We discuss the role of PDIL2;3 in retaining proteins within the ER and specifying their localization to PB-I through disulfide bond formation.