Rice (Oryza sativa L) alpha-amylase inhibitors of 14-16 kDa are potential allergens and products of a multigene family

Five proteins of 14-16 kDa (I-V), with cross-reactivity with antibodies specific for a previously isolated 16-kDa allergen, were purified from rice endosperm. The N-terminal amino acid sequences of these proteins suggested that four of them were products of previously isolated cDNA clones of a rice RA multigene family. All purified proteins showed inhibitory activity toward human salivary alpha-amylase, whereas they inhibited neither bacterial alpha-amylase nor bovine trypsin. Radioallergosorbent tests (RAST), using immunoglobulin class E (IgE) antibodies from patients allergic to rice, showed that the IgE from some patients reacted with all five proteins, whereas others specifically reacted with individual proteins. These results indicate that all five proteins characterized as alpha-amylase inhibitors are potentially allergenic.