Figure 1.

Nucleotide sequence of Xenopus proglucagon cDNAs I and II. The predicted amino acid sequence of Xenopus proglucagon I is shown above the cDNA sequences. The DNA sequence is numbered from the 5′ end of the longest cDNA, whereas the amino acid sequence is numbered from the predicted N terminus of proglucagon. Predicted glucagon and glucagon-like peptides are underlined. Potential proteolytic processing sites that yield C-terminally truncated GLP-1-like peptides are indicated by an arrow with a question mark (↓?). A polyadenlyation signal (AATAAA) at bases 1422–1427 is indicated in boldface type. Dashes are gaps introduced to yield maximal alignment. Xenopus proglucagon II cDNAs do not encode GLP-2, and some proglucagon I cDNAs had a homologous deletion, removing the GLP-2 sequence, due to alternative splicing.