- 1. Fe3+, Fe2+, Heme-Fe3+ is freed by HCl, proteases, etc from bound-nonheme iron and Hb/Mb
- 2. Heme Fe3+ enters enterocyte via hcp1 --> heme oxygenase: Fe2+ + protoporphryin
Fe3+ is reduced into Fe2+ and all Fe2+ is absorbed by DMT1
3. Fe2+ is bound to cytosolic protein then--> functional use in cell or stored as ferritin
5. Fe2+ is reoxidized to Fe3+ via hephaestin
6. Fe3+ is exported out of cell via ferroportin
7. Fe3+ is loaded on to apotransferrin --> transferrin-Fe3+
2. Upregulated by amount of available iron, downregulated by interaction with hepcidin
3. Must be reoxidized to Fe3+ so it can bind to transferrin for transport
4. Link between Fe-def and Cu-def, because admin of Cu helps export Fe out of tissues into circulation (hephaestin has homology with ceruloplasmin)
5. IRP1 and IRP2 are cytosolic RNA binding proteins that bind to IREs on mRNA of ferritin, TfR, DMT1. Binding of IRPs at 5' end of transcripts decreases rate of synthesis, while binding at 3' end prolongs halflife of mRNA --> increased synthesis.
In iron overload, decreased TfR/DMT and increased ferritin (for adequate storage) and vice versa!