J. Biol. Chem., Vol. 261, Issue 18, 8128-8133, 06, 1986
Isolation and structure of the principal products of preproglucagon processing, including an amidated glucagon-like peptide
PC Andrews, DH Hawke, TD Lee, K Legesse, BD Noe and JE Shively
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.