Proteomic Analysis of the Royal Jelly and Characterization of the Functions of its Derivation Glands in the Honeybee

To identify candidate royal jelly (RJ) proteins that might affect the physiologic status of honeybee colony members, we used shotgun proteomics to comprehensively identify the RJ proteome as well as proteomes of the hypopharyngeal gland (HpG), postcerebral gland (PcG), and thoracic gland (TG), from which RJ proteins are assumed to be derived. We identified a total of 38 nonredundant RJ proteins, including 22 putative secretory proteins and Insulin-like growth factor-binding protein complex acid labile subunit. Among them, 9 proteins were newly identified from RJ. Comparison of the RJ proteome with the HpG, PcG, and TG proteomes revealed that 17 of the 22 putative secretory RJ proteins were derived from some of these glands, suggesting that the RJ proteome is a cocktail of proteins from these three glands. Furthermore, pathway analysis suggested that the HpG proteome represents the molecular basis of the extremely high protein-synthesizing ability, whereas the PcG proteome suggests that the PcG functions as a reservoir for the volatile compounds and a primer pheromone. Finally, to further characterize the possible total RJ proteome, we identified putative secretory proteins in the proteomes of these three glands. This will be useful for predicting novel RJ protein components in future studies.