Abstract: Odorant binding proteins (OBPs) in insects play a primordial role in foraging, courtshipping, multiplying, and chemical communication with the environments. General odorant binding protein/pheromone binding protein (GOBP/PBP) is an important monophyletic group of Lepidoptera OBP family. We analyzed the GOBP/PBP in the silkworm Bombyx mori, the model organism of Lepidoptera, using chromosome mapping and semi-quantitative RT-PCR for further understanding of the expression and function of GOBP/PBP. Chromosome mapping showed that these genes were organized in the nscaf3052 of chromosome 19 in the form of gene cluster, with similar gene structure and identical transcription direction, suggesting that they were originated from the duplication of homologous genes and probably possess functional similarity. Analysis of the expression profiles in different tissues of males and females during pupal and adult stages revealed that these genes possessed conspicuous temporal and spatial expression differences (P<0.05), the highest relative expression level occurred in the antenna, and lower relative expression levels in other most non-olfactory tissues without significant sex differences. The results suggest that these genes may have other functions undiscovered besides olfactory-related function.

Key words: Bombyx mori, odorant binding protein (OBP), GOBP/PBP subfamily, gene cluster, expression analysis, chromosome mapping