No abstract

The maize b-70 protein is an endoplasmic reticulum protein overproduced in the floury-2 (f12) endosperm mutant. The increase in b-70 levels in f12 plants occurs during seed maturation and is endosperm specific. We have used amino acid sequence homology to identify b-70 as a homolog of mammalian immunoglobulin binding protein (BiP). In contrast, the f12 allele negatively affects the accumulation of the major endosperm storage proteins. The physical similarity of b-70 to BiP and its association with abnormal protein accumulation in f12 endoplasmic reticulum may reflect a biological function to mediate protein folding and assembly in maize endosperm.