Carboxypeptidase‐B‐like processing of the C‐terminus of glucagon‐like peptide‐2 in pig and human small intestine

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Abstract
We developed specific, C‐terminal radioimmunoassays for three proglucagon (PG) fragments: PG 151–158, PG 151–160 and PG 126–159 (glucagon‐like peptide‐2 (GLP‐2)) in order to determine the exact C‐terminal sequence of the newly isolated GLP‐2 in man and pig. The antigens and the antisera showed no mutual cross‐reactivity. By gel filtration of extracts of pig and human small intestine, the immunoreactivity eluting at the position of GLP‐2 was identified by the radioimmunoassays for glucagon‐like peptide‐2 (PG 126–159) and for PG 151–158, whereas the assay for PG 151–160 was completely negative. We conclude that the C‐terminal amino acid residue of pig and human ileal GLP‐2 is PG 158. Thus the basic residues, PG 159 and 160 are removed during its processing in the small intestine.