China
Africa
Explore chapters and articles related to this topic
Disorders of haem metabolism: iron and the porphyrias
Published in Martin Andrew Crook, Clinical Biochemistry & Metabolic Medicine, 2013
Body iron content control depends on absorption by an active process in the duodenum: free Fe2 + via the divalent metal transporter 1 (DMT-1) and haem-bound iron via the haem carrier protein 1. Within the enterocyte, some of the iron combines with the protein apoferritin to form ferritin. Free iron is exported from the enterocyte via ferroportin into the circulation where it binds with transferrin for transport and storage. Transferrin-bound iron then enters target cells via receptor-mediated endocytosis. Hepcidin is the main iron regulating protein, and inhibits ferroportin. Concentrations of hepcidin increase in iron overload and reduce in iron deficiency. The human haemochromatosis protein (HFE) regulates the binding of transferrin to the transferrin receptor as well as regulating hepcidin.
Iron homeostasis in host and gut bacteria – a complex interrelationship
Published in Gut Microbes, 2021
Yohannes Seyoum, Kaleab Baye, Christèle Humblot
Iron absorption takes place in the duodenum and is regulated by two distinct pathways, one for heme and the other for non-heme iron. Heme bound iron is taken up at the border of the duodenal brush, but the exact mechanism remains unclear. Heme carrier protein 1 (HCP1) and the heme responsive gene (HRG1) have been suggested as potential uptake transporters for heme iron, but HCP1 was recently proposed to be a folate transporter unrelated to heme. However, a more recent study suggested that HCP1 is involved in low-affinity heme-iron uptake and not only in folate transport.24 In this case, heme oxygenase 1 (HOX1) activity would catabolize cytosolic heme into ferrous iron, which presumably then joins the cellular labile iron pool. However, the mechanism of transport of ferrous iron to the labile iron pool is not known. Dietary non-heme iron in its non-bioavailable oxidized (ferric) form must first be reduced to the ferrous form by DCYTB, after which DMT1, which is expressed in the brush border membrane of duodenal enterocytes, transports it across the intestinal epithelium.25