Cytosol intermediates in the transport of iron
MT Nunez, ES Cole and J Glass
Three 59Fe-labeled nonheme components of the cytosol were identified when
rabbit reticuloyctes were incubated with 59Fe-labeled plasma under
conditions in which the iron supply was not limiting. Two of these
components were identified as ferritin and transferrin. The latter was
characterized by gel filtration as having apparent molecular weight higher
than transferrin, indicating that the transferrin may be complexed to
another moiety. The third component, referred to as iron- binding protein-I
(IBP-I), is as yet uncharacterized. When the reticulocytes were incubated
with unlabeled plasma after pulse-labeling with 59Fe-labeled plasma, 59Fe
radioactivity in these cytosol components decreased; after 15 min of chase,
the 59Fe in ferritin, transferrin, and IBP-I fell to 64.6%, 26.5%, and
65.8% of the initial values, respectively. A good correlation existed
between the decrease of 59Fe in these three nonheme compartments and the
associated increase in 59Fe-heme. The data presented suggest that cytosol
ferritin, transferrin, and IBP-I are intermediates in the transport of 59Fe
from the plasma membrane to the mitochondria.
Volume 55,
Issue 6,
pp. 1051-1055,
06/01/1980
Copyright © 1980 by The American Society of Hematology
