PDIL1-1 plays an essential role in the segregation of proglutelin and prolamin polypeptides within the ER lumen (Takemoto et al., 2002). OsPDIL1-1 expression is observed throughout the plant, but most intensely in the developing grain. Seeds of the T-DNA insertion mutants of OsPDIL1-1 display a chalky endosperm with thick aleurone layer and significantly lower amount of protein content (Kim et al., 2012). Somaclonal mutant of OsPDIL1-1 produces small grains with a floury endosperm, caused by the loose packing of starch granules. Abolished function of OsPDIL1-1 results in decreased activity of plastidial phosphorylase and pullulanase, and an increase in that of soluble starch synthase I and ADP-glucose pyrophosphorylase. The amylopectin in the endosperm of mutant seeds shows an increase in chains with a degree of polymerization (Han et al., 2012).