Coated vesicles from chicken liver bind ferritin

The iron-storage protein ferritin was found to be associated with highly purified coated vesicles (CV) from chicken liver. Chicken liver ferritin was morphologically similar to ferritin from horse spleen and could be isolated using a specific anti-ferritin monoclonal antibody. This antibody recognized a 240 X 10(3) Mr form of chicken ferritin but not the 22 X 10(3) Mr ferritin subunit after protein transfer to nitrocellulose. CV purified by controlled-pore glass-bead chromatography also contained ferritin when assayed by monoclonal anti-ferritin antibody using a sensitive enzyme-linked assay. Ferritin remained associated with CV even after re-chromatography. Ferritin particles were observed to be associated with CV by electron microscopy. CV-associated ferritin could be quantitatively removed from CV by treatment of the CV with 0.5 M-Tris-HC1 + 2M-urea at pH 8.5, conditions that also lead to dissociation of the clathrin lattice. Triton X-100 detergent treatment did not affect the association of ferritin with CV. These results indicate that purified CV from chicken liver contain ferritin in association with the clathrin lattice. The possible functional significance of this association is discussed.