The fourth instar in the silk gland of silkworm LC-MSMS

In the present study, the silk gland proteomes of the fourth instar and fourth molt were analyzed using liquid chromatography−tandem mass spectrometry. In total, 2654 proteins were identified from the silk gland. High abundance of ribosomal proteins and RR-motif chitin-binding proteins were identified during day 2 of the fourth instar (IV-2) larval developmental stage, and the expression of cuticular proteins analogous to peritrophin (CPAP)-motif chitin-binding proteins was higher during the fourth molt (IV-M). In all, nine enzymes were found to be involved in the chitin regeneration pathway in the silk gland. Among them, two chitinase and two chitin deacetylases were identified as CPAP-motif proteins.