Regulation of the Expression of Cathepsin B in Sarcophaga Peregrina (Flesh Fly) at the Translational Level During Metamorphosis

Previously, we reported that cathepsin B of pupal hemocytes participates in dissociation of the fat body of Sarcophaga larvae at metamorphosis. In this study, we demonstrated that the amount of cathepsin B in hemocytes was controlled at the translational level, i.e. larval hemocytes stored a significant amount of untranslated cathepsin B mRNA. When the larvae pupated, translation of the mRNA commenced, resulting in accumulation of cathepsin B. Our results indicate that the 3′‐untransJated region (3′‐UTR) of this mRNA is necessary for the repression of its translation in a rabbit reticulocyte lysate. We detected the 3′‐UTR binding protein in the lysate of larval hemocytes, but not in the pupal hemocytes. The role of this protein in the translation of cathepsin B mRNA is discussed.