Mutations in the guinea pig preproglucagon gene are restricted to a specific portion of the prohormone sequence.

A cDNA clone encoding guinea pig preproglucagon has been isolated from a pancreatic cDNA library. The predicted amino acid sequence of proglucagon is highly conserved in all regions, in comparison to other mammals, except for the C-terminal portion of the 29-residue glucagon region, in which 5 amino acid substitutions have occurred. These changes may serve to offset the reduced receptor-binding potency of the highly mutated insulin in this New World species.