Peptide hormones and neuropeptides. Proteolytic processing of the precursor regulatory peptides

Regulatory peptides are initially synthesized as large protein precursors which must undergo proteolytic processing to yield the biologically active peptide. The proteolytic enzymes involved in this post-translational processing remove the signal peptide, a hydrophobic peptide located at the amino-terminus of the precursor. Further processing steps are the cleavage at single or two adjacent basic residues by endoproteases, followed by a removal of basic residues located at the C-terminus of the peptides by a carboxypeptidase-like enzyme. The selective processing may play an important role in determining which peptides are finally released by the cell. This article reviews the selectivities of various enzymes known to play a role in the proteolytic processing of various regulatory peptides.