Involved in protein body development and 22 kDa alpha-zein localization. Interacts (via C-terminus) with both 22 kDa and 19 kDa alpha-zeins (PubMed:17693529). Interacts (via C-terminus) with OP10 (via N-terminus) (PubMed:27541862). Found in the endoplasmic reticulum surrounding the protein body, but not in the cisternal membranes. Expressed in endosperm. Not detected in embryo, leaves and roots. Accumulates at a high level in endosperm during the period of zein synthesis and protein body development and declines to a low level at kernel maturity.