Little gastrin I is a form of

gastrin Gastrin is a peptide hormone that stimulates secretion of gastric acid (HCl) by the parietal cells of the stomach and aids in gastric motility. It is released by G cells in the pyloric antrum of the stomach, duodenum, and the pancreas. Gastrin ...

commonly called as gastrin-17. This is a protein hormone, secreted by the intestine. Gastrin II has identical amino acid composition to Gastrin I, the only difference is that the single tyrosine residue is sulfated in Gastrin II.

References

Peptide hormones {{biochem-stub