Identification of an intestinal heme transporter

Dietary heme iron is an important nutritional source of iron in carnivores and omnivores that is more readily absorbed than non-heme iron derived from vegetables and grain. Most heme is absorbed in the proximal intestine, with absorptive capacity decreasing distally. We utilized a subtractive hybridization approach to isolate a heme transporter from duodenum by taking advantage of the intestinal gradient for heme absorption. Here we show a membrane protein named HCP1 (heme carrier protein 1), with homology to bacterial metal-tetracycIine transporters, mediates heme uptake by cells in a temperature-dependent and saturable manner. HCP1 mRNA was highly expressed in duodenum and regulated by hypoxia. HCP1 protein was iron regulated and localized to the brush-border membrane of duodenal enterocytes in iron deficiency.