A novel protease in the pupal yellow body of Sarcophaga peregrina (flesh fly). Its purification and cDNA cloning.

We purified a novel serine protease with a molecular mass of 26 kDa from Sarcophaga pupae. This protease appeared almost exclusively in the yellow body, an organ that develops temporarily in the pupae of dipteran insects and expands to form the adult midgut by engulfing the larval midgut. cDNA analysis revealed that this protease consists of 239 amino acid residues and has significant structural similarity with bovine trypsin (about 40% sequence identity). The 26-kDa protease gene was transiently activated in 1-day-old pupae. The protease was found to cross-react immunologically with antibody against sarcotoxin IA, an antibacterial protein produced by this insect. It is suggested that this protease participates in the decomposition of the larval midgut in the yellow body during metamorphosis.