Cereal endosperm protein required for the ring-shaped distribution of 22 kDa alpha- and 16 kDa gamma-zeins in protein bodies. Homodimer (PubMed:27541862). Interacts (via N-terminus) with FL1 (via C-terminus), HIP, 19 kDa alpha-zein (AC P06677), 22 kDa alpha-zein (AC O48966), 16 kDa gamma-zein (AC P08031) and 50 kDa gamma-zein (AC C0P381) (PubMed:27541862). In endosperm, predominantly deposited into protein bodies, at the interface between the alpha-zein-rich region and the gamma-zein-rich region. Expressed in kernels. Expressed continuously during kernel development. The seven repeat domain is responsible for dimerization.