The effect of β-ecdysone on protein synthesis in imaginal discs of Drosophila melanogaster cultured in vitro: II. Effects on synthesis in specific cell fractions

Abstract

The effect of β-ecdysone on the synthesis of different proteins in imaginal discs of Drosophila melanogaster was investigated using double-label experiments and SDS acrylamide gel electrophoresis. Four different cellular fractions were analyzed (12K pellet, cytosol, core ribosomes, and KCl-soluble ribosomal proteins). β-Ecdysone alters the net synthesis of proteins in all of these fractions, with the most dramatic effects occurring in the ribosomal protein fractions. The maintenance of the altered pattern of synthesis of proteins in these fractions depends on the continued presence of β-ecdysone in the culture medium. The data suggest that β-ecdysone alters the synthesis of different proteins by acting on the genome. The apparent mechanisms by which β-ecdysone increases total protein synthesis and alters the net synthesis of different proteins in discs are discussed.