Since TAGs are the bombykol precursors, they play import roles in sex pheromone biosynthesis and release. However TAG biosynthesis and storage are rarely investigated. Our previous study revealed that diacylglycerol acyltransferase 2 (DGAT) catalyses the final step in TAG biosynthesis, RNAi knockdown of DGAT causes a substantial decrease in sex pheromone production9. However TAG biosynthesis consists of two pathways, namely the monoacylglycerol (MAG) pathway and glycerol phosphate pathway (GAP). The MAG and GAP pathways share a common final step which is controlled by DGAT. The results of proteomics show an increase in GPAT protein level at key stage of sex pheromone biosynthesis. GPAT catalyses the first step in TAG biosynthesis via GAP, namely the conversion of glycerol 3-phosphate and acyl-CoA into 1-acylglycerol-3- phosphate. GPAT has the lowest enzyme specific activity in this pathway, thus it has been considered to be a speed-limiting enzyme for TAG biosynthesis via GAP19. Four GPAT isoforms have been identified in mammalian animals. GPAT1 and GPAT2 are mitochondrial isoforms, and GPAT3 and GPAT4 are ER membrane isoforms20. The present iTRAQ-based proteomics identified a GPAT homologue in B. mori (BmGPAT) (Table 1). The homologue was highly expressed in the 0 and 72 h PG samples at the translational levels (Fig. 4B), this finding was consistent with the transcript profile of BmGPAT (Fig. 4C). Sequence analysis indicated that the amino sequence encoded by BmGPAT showed 31% identity with that of human GPAT1, suggesting that the BmGPAT identified in PGs was a GPAT1 isoform (data not shown).