Sericins are hydrophilic structural proteins produced by caterpillars in the middle section of silk glands and layered over fibroin proteins secreted in the posterior section. In the process of spinning, fibroins form strong solid filaments, while sericins seal the pair of filaments into a single fiber and glue the fiber into a cocoon. Galleria mellonella and the previously examined Bombyx mori harbor three sericin genes that encode proteins containing long repetitive regions. Galleria sericin genes are similar to each other and the protein repeats are built from short and extremely serine-rich motifs, while Bombyx sericin genes are diversified and encode proteins with long and complex repeats. Developmental changes in sericin properties are controlled at the level of gene expression and splicing. In Galleria , MG-1 sericin is produced throughout larval life until the wandering stage, while the production of MG-2 and MG-3 reaches a peak during cocoon spinning.

Entomological Institute Biology Centre ASCR Branišovská 31 370 05 České Budějovice Czech Republic

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Absence of fibroin H sequences and a significant divergence in the putative fibroin L homolog in Neomicropteryx cornuta (Micropterigidae) silk

Genome sequence and silkomics of the spindle ermine moth, Yponomeuta cagnagella, representing the early diverging lineage of the ditrysian Lepidoptera

Modular structure, sequence diversification and appropriate nomenclature of seroins produced in the silk glands of Lepidoptera