GASTRIN extracted from human intestine has two main molecular forms, little (G17) and big (G34) gastrins1. Both these peptides are also found in antral tissue although their relative proportions differ, G17 being the major component in antral tissue and G34 that in intestinal tissue1. The endocrine cell associated with the production of the immunoreactive gastrin found in the antral tissue is the ultrastructurally classified G cell 2. The cellular origin of the immunoreactive gastrin extracted from the intestinal tissue has not been determined. The presence of cholecystokinin (CCK) peptides3,4, closely related to gastrin and sharing with it a C-terminal pentapeptide sequence (see Fig. 1), makes the specific immunological detection of both gastrin and CCK dependent on the use of well characterised and highly specific antibodies. We report here the finding that intestinal gastrin originates in a type of cell totally distinct from the I cell which has recently been identified as the source of CCK5.
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