Specific end-product feedback regulation of pancreatic protein synthesis

The potential for negative feedback regulation of the synthesis of individual enzymes was tested in the rabbit pancreas. Tissues were preincubated with individual pancreatic enzymes under conditions which have been shown to allow significant tissue absorption of these enzymes. The rates of synthesis of total proteins and amylase were then measured by following incorporation of labeled amino acids. Preincubation of lobules with amylase in the bath caused amylase synthesis to be inhibited by 50% without significantly inhibiting total protein synthesis. Preincubation of lobules with chymotrypsinogen significantly inhibited total protein synthesis without significantly inhibiting amylase synthesis. These data demonstrate specific end-product feed-back inhibition of protein synthesis in eukaryotes and may represent a pattern for regulation of protein synthesis in general.