Relationship of glicentin to proglucagon and glucagon in the porcine pancreas.

We have previously isolated from porcine small intestine a peptide known as glicentin. The C-terminal portion of glicentin consists of the sequence of glucagon extended at its C terminus by an octapeptide, and differs slightly from the sequence of a proposed fragment of proglucagon. Glicentin-like material has been demonstrated in the pancreatic A cell, wherein it is located in the periphery of the secretory granules, whereas glucagon is located in the centre of the granules. To study the relationship of glicentin to the biosynthesis of glucagon, we have now investigated the glucagon-like and glicentin-like peptides in extracts and perfusates of the porcine pancreas. Our findings that a peptide with glicentin-like immunoreactivity, and intermediate in size between glicentin and glucagon, is secreted synchronously with glucagon suggest that this glicentin-related peptide is a major cleavage product of proglucagon.