Proteomic analysis of rice allergens in red rice and black rice

Abstract

The levels and features of the allergenic proteins in six cultivars of red or black rice were compared with those in white rice. The two major allergens of rice, the RAG2 family allergenic protein isoforms and the glyoxalase I protein, were targeted so as to compare their contents in the cultivars using immunoblotting and two-dimensional difference gel electrophoresis (2D-DIGE), as a proteomic analytical method. The immunoblotting results showed that the amounts of RAG2 isoforms were lower in some cultivars of the red and black rice than those of the white rice, while all the cultivars contained similar levels of glyoxalase I. The results of 2D-DIGE showed that some cultivars contained significantly fewer RAG2 isoforms (including RAG1 [RA17], RAG2 [RA14], and allergenic protein [18kDa]) than white rice. Similar to the immunoblotting results, the contents of glyoxalase I protein were similar among all the cultivars. The differences in the composition of the allergen proteins among the cultivars may have been dependent not on the color of the bran but on the genetic background of the cultivars based on a pattern analysis. Here, we present the differences in the contents of the isoforms of the allergenic proteins in ancient rice cultivars using the 2D-DIGE method.