The biological significance of "enteroglucagon." Present status

"Enteroglucagon" refers to glucagon-like peptides present in intestine that cross react with N-terminally directed antiglucagon antisera but not with C-terminally directed antisera. Two peptides having these features have been isolated from the lower small intestine: glicentin (69 amino acids) and oxyntomodulin (37 amino acids). The sequence of the pancreatic preproglucagon gene suggests that glucagon, glicentin and oxyntomodulin derive from the same translational pathway, each individual peptide being produced by different posttranslational processing. Both glicentin and oxyntomodulin contain the glucagon sequence that bears the N-terminal epitope and are C-terminally extended by the same octapeptide masking the C-terminal epitope. The N-terminal 32 amino acid extension of glicentin renders the molecule unable to bind to hepatic glucagon receptors, unlike glucagon and oxyntomodulin. An original tissue specificity of oxyntomodulin, mediated by a novel type of receptor, has been observed in acid secreting gastric oxyntic glands. Oxyntomodulin and glicentin containing the C-terminal octapeptide, as well as the octapeptide itself, are able to inhibit gastric acid secretion. This biological activity is likely to represent the main physiological regulatory pattern in which "Enteroglucagon" is involved.