Ferritin as a cytosol iron transport intermediate in human reticulocytes

BE Speyer, J Fielding - British Journal of Haematology, 1979 - Wiley Online Library
BE Speyer, J Fielding
British Journal of Haematology, 1979Wiley Online Library
The major iron‐bearing cytosol components of human reticulocytes identified after
incubation with 59Fe–125I‐transferrin have been studied further. Component C previously
found to behave consistently as an intermediate in the iron transport pathway to haem is
shown to consist entirely of ferritin. After a short pulse of labelled transferrin incubation,
chase experiments showed a fall of ferritin label with time and a corresponding increase in
haemoglobin‐iron incorporation. There was no loss of ferritin to the culture medium …
Summary. The major iron‐bearing cytosol components of human reticulocytes identified after incubation with 59Fe–125I‐transferrin have been studied further. Component C previously found to behave consistently as an intermediate in the iron transport pathway to haem is shown to consist entirely of ferritin. After a short pulse of labelled transferrin incubation, chase experiments showed a fall of ferritin label with time and a corresponding increase in haemoglobin‐iron incorporation. There was no loss of ferritin to the culture medium. Restriction of iron uptake by reticulocytes using both p‐hydroxymercuribenzoate inhibition of uptake and incubation with progressively lower saturations of iron‐transferrin gave linearly related incorporation of 59Fe into ferritin and haemoglobin at all levels of iron uptake, thus negating the concept of ferritin as an ‘overspill’ form of reticulocyte iron. The results suggest that cytosol ferritin is an obligatory intermediate in reticulocyte iron transport.
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