Shotgun analysis on the peritrophic membrane of the silkworm Bombyx mori

The insect midgut epithelium is generally lined with a uniquechitin and protein structure, the peritrophic membrane (PM),which facilitates food digestion and protects the gut epithelium.We used gel electrophoresis and mass spectrometry toidentify the extracted proteins from the silkworm PM to obtainan in-depth understanding of the biological function of thesilkworm PM components. A total of 305 proteins, with molecularweights ranging from 8.02 kDa to 788.52 kDa and theisoelectric points ranging from 3.39 to 12.91, were successfullyidentified. We also found several major classes of PMproteins, i.e. PM chitin-binding protein, invertebrate intestinalmucin, and chitin deacetylase. The protein profile provides abasis for further study of the physiological events in the PM ofBombyx mori.