Like human Gastrin-1 “Little Gastrin,” rat Gastrin-1 “Little Gastrin” contains 17 amino acids, but differs from human Gastrin by 3 amino acids at the C-terminus. Secretion of Gastrin is induced by food intake and causes the release of gastric acid. Synthesized by the G cells in the gastric mucosa, it is one of the major bioactive forms of Gastrin (the other bioactive form is Gastrin-34). Both Gastrin-17 and Gastrin-34 are carboxy-amidated and partially tyrosine sulfated. Binding of Gastrin to the CCK2/gastrin receptor requires carboxy-amidation, however sulfation is not necessary for binding to the receptor.