Proteomic analysis of secreted proteins from the ectoperitrophic space of Bombyx mori

The samples from the ectoperitrophic space of Bombyx mori were collected at different developmental stages. The three samples at wandering stage were labeled with the isobaric tags 126, 127 and 128 respectively; whereas the three samples at feeding stage were labeled with the isobaric tags 129, 130 and 131 respectively. The same amount of the six labeled samples were mixed together as one sample for analysis on LTQ Orbitrap Velos. Four technical replicates of each sample were analyzed. The protein expression levels during different developmental stages were compared to each other according to the different isobaric tags. A total of 372 proteins were identified from the ectoperitrophic space and 37 proteins were up-regulated at feeding stage while 41 proteins were up-regulated at wandering stage. Novel proteins were identified by proteomic analysis and essential proteins were found specifically expressed at feeding or wandering stage.