Ferritin associates with marginal band microtubules.
We characterized chicken erythrocyte and human platelet ferritin by biochemical studies and immunofluorescence. Erythrocyte ferritin was found to be a homopolymer of H-ferritin subunits, resistant to proteinase K digestion, heat stable, and contained iron. In mature chicken erythrocytes and human platelets, ferritin was localized at the marginal band, a ring-shaped peripheral microtubule bundle, and displayed properties of bona fide microtubule-associated proteins such as tau. Red blood cell ferritin association with the marginal band was confirmed by temperature-induced disassembly-reassembly of microtubules. During erythrocyte differentiation, ferritin co-localized with coalescing microtubules during marginal band formation. In addition, ferritin was found in the nuclei of mature erythrocytes, but was not detectable in those of bone marrow erythrocyte precursors. These results suggest that ferritin has a function in marginal band formation and possibly in protection of the marginal band from damaging effects of reactive oxygen species by sequestering iron in the mature erythrocyte. Moreover, our data suggest that ferritin and syncolin, a previously identified erythrocyte microtubule-associated protein, are identical. Nuclear ferritin might contribute to transcriptional silencing or, alternatively, constitute a ferritin reservoir.
Infante
Anthony A
AA
Department of Molecular Biology and Biochemistry, Wesleyan University, Middletown, CT 06459, USA.
Infante
Dzintra
D
Chan
Muh-Chun
MC
How
Poh-Choo
PC
Kutschera
Waltraud
W
Linhartová
Irena
I
Müllner
Ernst W
EW
Wiche
Gerhard
G
Propst
Friedrich
F
D000595:Amino Acid Sequence; D000818:Animals; D001052:Apoferritins / Q000235:genetics / Q000378:metabolism; D001792:Blood Platelets / Q000166:cytology* / Q000378:metabolism; D002454:Cell Differentiation; D002642:Chick Embryo; D002645:Chickens; D004912:Erythrocytes / Q000166:cytology* / Q000378:metabolism; D004920:Erythropoiesis; D005293:Ferritins / Q000235:genetics / Q000378:metabolism*; D015723:Gene Library; D020868:Gene Silencing; D006801:Humans; D008870:Microtubules / Q000378:metabolism*; D008969:Molecular Sequence Data; D017382:Reactive Oxygen Species / Q000378:metabolism
D017382:Reactive Oxygen Species; D005293:Ferritins; D001052:Apoferritins