ABSTRACT
The pathways delineating the production of particular neuropeptides, including those having multi-potential precursors, have been largely established. It appears that a relatively small number of enzymes are involved in the proteolytic processing steps that generate the active neuropeptides. The internal structural similarities between neuroactive peptides and other bioactive peptides from other tissues allow us to consider them as members of families of peptides. The glycine residue just N-terminal to the pair of basic residues in the precursor is required as a signal for the peptide to be amidated. Glucagon is encoded by a preprohormone which contains in tandem the sequences of glucagon and two additional glucagon-like peptides that are structurally related to glucagon and are separated by intervening peptides. The general structure of the pro Thyrotropin-Releasing Hormone gene is similar to that of the other multi-precursor genes in which single exons encode the bioactive peptides.
