Labels:text | screenshot | black and white | black | font | document OCR: ic antrum Gastrin is produced by G cells in the gas and upper (from which it was first isolated in 1905) molecular small intestine and exists in a variety of eventeen, forms. The principal ones are fourteen, latter beingor thirty-four amino acids in length, the rt of the described as 'big gastrin'. The bioactive p terminal molecule is the four amino-acid carboxy sequence, which is common to all. The are G17 predominant circulating forms of gastrir ll intestine.from the stomach and G34 from the sma me five G17 has a half-life in the circulation of s roximately minutes, while G34 has a half-life of app re almost forty minutes; the two forms, however, equipotent