The encoded polypeptide is preprogastrin, which is cleaved by enzymes in posttranslational modification to produce progastrin (an intermediate, inactive precursor) and then gastrin in various forms, primarily the following three: Also, pentagastrin is an artificially synthesized, five amino acid sequence identical to the last five amino acid sequence at the C-terminus end of gastrin.

[17] In autoimmune gastritis, the immune system attacks the parietal cells leading to hypochlorhydria low stomach acid secretion.

Eventually, all the parietal cells are lost and achlorhydria results leading to a loss of negative feedback on gastrin secretion.

Plasma gastrin concentration is elevated in virtually all individuals with mucolipidosis type IV (mean 1507 pg/mL; range 400-4100 pg/mL) (normal 0-200 pg/mL) secondary to a constitutive achlorhydria.

[19] Its existence was first suggested in 1905 by the British physiologist John Sydney Edkins,[20][21] and gastrins were isolated in 1964 by Hilda Tracy and Roderic Alfred Gregory at the University of Liverpool.