Molecular and cellular regulation of prohormone processing

The processing of prohormones involves cleavage at specific basic amino acids by members of the subtilisin-like serine endoprotease family, followed by trimming of the COOH terminus by carboxypeptidase E. The enzymes are regulated by the intra-organelle ionic environment, through postranslational processing and by interaction with endogenous inhibitors. Much has been learned about their catalytic function and cell biology from in vitro gene transfer experiments using chimeric molecules and by site-directed mutagenesis. Further insight into their molecular properties and physiological function has been gained recently from the study of in vivo mutants.