Function of Integrin in Duodenal Mucosal Uptake of Iron

A mechanism for the absorption of inorganic iron in the small intestine is described in which integrins appear to play an important role in the passage of iron across microvillous membranes. Biochemical isolates from microvillous preparations of duodenum from rats dosed with radioiron showed radioactivity concentrated in integrins. The presence of integrins on mucosal surfaces of duodenal cells was confirmed by immunofluorescent microscopy using anti-integrin monoclonal antibodies. Immunoprecipitation methods were used to show that microvillous radioiron was precipitated with anti-integrin antibodies and that mobilferrin, a 56-Kd cytosol iron-binding protein, coprecipitated with integrins. We postulate from these data that the mucosal uptake of iron from the gut lumen is mediated via an integrin-mobilferrin pathway.