Biosynthesis of neuronal peptides: implications for neurobiology.

Many biologically active peptides (e.g., insulin, nerve growth factor, ACTH, endorphin, parathyroid hormone, etc.) appear to be synthesized first as prohormones, which are then converted intracellularly to the biologically active products by various post-translational modifications. Peptides of neuronal origin (e.g., vasopressin and oxytocin) are synthesized by similar mechanisms. The prominent role of post-translational processing in determining the final peptide products allows for the possibility that different peptides will by generated from identical prohormones in different cells.