Table 1. Amino acid sequence of the most important members of the gastrin/CCK family.

Natural ligand	Amino acid sequence*
Gastrin-17 (gastrin-I)	Glp-Gly-Pro-Trp-Leu-Glu-Glu-Glu-Glu-Glu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2
Gastrin-13 (minigastrin)	Leu-Glu-Glu-Glu-Glu-Glu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2
Cholecystokinin-8 (CCK-8)	Asp-Tyr-Met-Gly-Trp-Met-Asp-Phe-NH2
Cholecystokinin-4 (CCK-4)	Trp-Met-Asp-Phe-NH2

^*bold letters = amino acids known to be involved in receptor binding