Isolation and structure of the principal products of preproglucagon processing, including an amidated glucagon-like peptide.
The principal products derived from in vivo processing of anglerfish preproglucagon II were isolated and their structures determined. The structures were confirmed by a combination of automated Edman degradation, amino acid analysis, and fast atom bombardment mass spectrometry. The peptide corresponding to anglerfish preproglucagon II-(22-49) (numbering from the amino terminus of preproglucagon) was isolated intact and defines the site of signal cleavage to be between Gln-21 and Met-22. Glucagon from the anglerfish preproglucagon gene II was found to correspond to preproglucagon II-(52-80) (numbering from the amino terminus). Three forms of a glucagon-like peptide derived from preproglucagon II were also isolated. The structure of the longest form was consistent with the sequence of preproglucagon II-(89-122) deduced from the cDNA, His-Ala-Asp-Gly-Thr-Tyr-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Gln-Asp-Gln-Ala- Ala-Lys-Asp-Phe-Val-Ser-Trp-Leu-Lys-Ala-Gly-Arg-Gly-Arg-Arg-Glu. The carboxyl-terminal portion deduced from the cDNA remains intact in this form. A second form, preproglucagon II-(89-119) appears to result from proteolytic processing of the major form at the two adjacent arginine residues occurring at the carboxyl terminus. This second form has a glycine residue at its carboxyl terminus and is processed to the third form (preproglucagon II-(89-118)) which contains a carboxyl-terminal arginineamide. Radiolabeling studies in primary tissue culture support the observation that glucagon (preproglucagon II-(52-80], preproglucagon II-(89-122), and preproglucagon II-(89-119) are products of proglucagon processing in vivo.
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000032:analysis; D005399:Fishes; D005934:Glucagon / Q000032:analysis / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D013058:Mass Spectrometry; D052336:Proglucagon; D011498:Protein Precursors / Q000032:analysis / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D013045:Species Specificity
D000596:Amino Acids; D011498:Protein Precursors; D052336:Proglucagon; D004247:DNA; D005934:Glucagon