Molecular forms of glucagon-like peptides in man

Molecular forms of the glucagon-like peptides (GLP) encoded by the human preproglucagon gene were analysed by chromatography combined with specific radioimmunoassays to the synthetic peptides. Whereas extracts of human pancreas and a glucagonoma contained a large proglucagon cleavage product possessing both GLP-1 and GLP-2 immunoreactivities, extracts of human intestine contained products corresponding to free GLP-1 and a small amount of chromatographically distinct GLP-2 immunoreactivity. It is concluded that post-translational processing of proglucagon differs in pancreas and intestine, so that the C-terminal portion of the molecule is cleaved to liberate free GLP-1 in the intestine. Further processing or degradation results in loss especially of GLP-2 immunoreactivity.