Metal ion-dependent binding of gastrin to albumin

A hypothesis of couplet molecules and couplet cells in gastric function and an association with Helicobacter pylori

Background

Gastrin, from G-cells, and histamine, from enterochromaffin-like (ECL) cells, are two of the hormones that regulate gastric activity.

Discussion

It is proposed that the G-cells and the ECL cells are coupled by the couplet molecules gastrin and histamine and by a prior asymmetrical cell division. The gastrin (from G-cells) stimulates the ECL cells to produce and secrete histamine while, in a reciprocal way, this histamine (from ECL cells), stimulates the G-cells to produce and secrete gastrin. These molecules would also stimulate cell division – the gastrin would stimulate cell division of ECL cells while histamine would stimulate that of G-cells. A chemical complex of gastrin and histamine is postulated as is also the asymmetric cell divisions of precursor cells to produce the coupled G-cells and ECL cells.

Conclusion

There is sufficient evidence to support the feasibility of the model in general, but more direct experimental evidence is required to validate the model as applied here to gastric function.

A new role for an old hormone: is gastrin a cofactor for dietary metal ion uptake?

It is proposed that gastrin promotes the uptake of divalent and trivalent metal ions from the gastrointestinal lumen by catalyzing the binding of metal ions to luminal albumin and transferrin respectively. The following observations are consistent with this hypothesis: 1. Gastrin binds both divalent and trivalent metal ions. 2. Gastrin binds to both albumin and apotransferrin. 3. Binding of gastrin to albumin is enhanced by divalent metal ions. 4. Gastrin, albumin and transferrin are all present in gastric juice. 5. Surgical removal of the gastric mucosa results in iron deficiency.