FIGURE 1.

Post-translational processing of proglucagon to its derived peptides. Numbers indicate amino acid positions relative to proglucagon, beginning at the N-terminal amino acid. The top and bottom rows represent processing sites and removal of spacer amino acids between peptides. Major hormone products produced from tissue-specific processing by prohormone convertases are shown at bottom. GRPP, glicentin-related pancreatic polypeptide; IP, intervening peptide; GLP, glucagon-like peptide; MPGF, major proglucagon fragment; PC, prohormone convertase.