Rates of iron uptake and heme synthesis, SIH- and DP-interceptable Fe in reticulocytes obtained from

mk/+ or mk/mk mice.Tf-associated Fe uptake and its subsequent utilization for heme synthesis as well as Fe release from Tf and its subsequent reduction in the endosomal lumen of mk/mk reticulocytes were investigated using Tf- labeled with ⁵⁹Fe and 2 membrane permeable Fe chelators, SIH (binds Fe⁺⁺⁺ and Fe⁺⁺) and DP (binds Fe⁺⁺ only). The results obtained withmk/mk reticulocytes (black bars) were compared with those obtained using reticulocytes from EPO-treated mk/+ mice (white bars). Compared to mk/+, in mk/mkreticulocytes, total cellular ⁵⁹Fe uptake and the rate of heme synthesis are reduced whereas the rate of ⁵⁹Fe transfer from ⁵⁹Fe-Tf to DP or SIH are unchanged .