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Characterization and Distribution of Ferritin Binding Sites in the Adult Mouse Brain
Author(s) -
Hulet S. W.,
Hess E. J.,
Debinski W.,
Arosio P.,
Bruce K.,
Powers S.,
Connor J. R.
Publication year - 1999
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1999.720868.x
Subject(s) - ferritin , transferrin receptor , transferrin , binding site , iron binding proteins , receptor , human brain , biochemistry , white matter , chemistry , biology , plasma protein binding , binding protein , medicine , neuroscience , radiology , gene , magnetic resonance imaging
: Studies on iron uptake into the brain have traditionallyfocused on transport by transferrin. However, transferrin receptors are notfound in all brain regions and are especially low in white matter tracts wherehigh iron concentrations have been reported. Several lines of research suggestthat a receptor for ferritin, the intracellular storage protein for iron, mayexist. We present, herein, evidence for ferritin binding sites in the brainsof adult mice. Autoradiographic studies using 125 I‐recombinanthuman ferritin demonstrate that ferritin binding sites in brain arepredominantly in white matter. Saturation binding analyses revealed a singleclass of binding sites with a dissociation constant ( K D )of 4.65 × 10 ‐9 M and a binding site density( B max ) of 17.9 fmol bound/μg of protein. Binding of radiolabeled ferritin can be competitively displaced by an excess of ferritin but not transferrin. Ferritin has previously been shown to affect cellular proliferation, protect cells from oxidative damage, and deliver iron. The significance of a cellular ferritin receptor is that ferritin is capable of delivering 2,000 times more iron per mole of protein than transferrin. The distribution of ferritin binding sites in brain vis‐à‐vis transferrin receptor distribution suggests distinct methods for iron delivery between gray and whi