Figure 1.

Amino acid sequence alignment of GLP-1 and its family peptides. Amino acid sequences of human GLP-1, GLP-2, glucagon, GIP, and Gila monster exendin are aligned. Residues in red are conserved sequences within orthologs of vertebrates including mouse, anole, chicken, Xenopus tropicalis, medaka, fugu, tetraodon, stickleback, and zebrafish. The residues colored in blue represent conserved sequences across paralogs. The residues in black are variable sequences. Underlines indicate the α-helical conformation. The residues responsible for interaction with their receptor are shaded.