Characterization of royal jelly proteins in both Africanized and European honeybees (Apis mellifera) by two-dimensional gel electrophoresis

In this study, the proteins contained in royal jelly (RJ) produced by Africanized honeybees and European honeybees (Apis mellifera) haven been analyzed in detail and compared using two-dimensional gel electrophoresis, and the N-terminal amino acid sequence of each spot has been determined. Most spots were assigned to major royal jelly proteins (MRJPs). Remarkable differences were found in the heterogeneity of the MRJPs, in particular MRJP3, in terms of molecular weights and isoelectric points between the two species of RJ. Furthermore, during the determination of the N-terminal amino acid sequence of each spot, for the first time, MRJP4 protein has been identified, the existence of which had been only implied by cloning of its cDNA sequence. The presence of heterogeneous bands of glucose oxidase was also identified. Thus, the results suggest that two-dimensional gel electrophoresis provides a suitable method for the qualitative analysis of the proteins contained in RJ derived from different honeybee species.