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Characterization of a ferritin isolated from the midgut epithelial cells of a homopteran insect, Philaenus spumarius L.
Author(s) -
Collin Olivier,
Thomas Daniel,
Flifla Mohammed,
Quintana Carmen,
Gouranton Jean
Publication year - 1988
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1111/j.1768-322x.1988.tb00753.x
Subject(s) - biology , ferritin , electron microscope , protein subunit , midgut , cytoplasm , ultrastructure , nucleus , insect , crystallography , biophysics , biochemistry , microbiology and biotechnology , botany , chemistry , gene , physics , larva , optics
Crystalline accumulations of ferritin‐like particles are present within the cytoplasm and the nucleus in midgut epithelial cells of the homopteran Philaenus spumarius . A structural study at the electron microscope level reveals that these particles have the morphological characteristics of the ferritin molecule: crystals have a face‐centered cubic structure with a lattice parameter of 14 ± 1 nm; negatively stained isolated particles have the appearance of ferritin; on rotary‐shadowed particles 3 axes of symmetry are clearly seen; image processing performed on selected molecules demonstrates a 4‐fold symmetry. A semiquantitative electron microprobe analysis effected on aggregates of microcrystals in thin sections reveals a high atomic ratio Fe/P. Analyzed by SDS‐PAGE, the protein subunit has a molecular weight of 18,600. The amino acid composition of the protein bears the general characteristics of the ferritin molecule in terms of polar and nonpolar residues. But in terms of sequences, this protein displays a strong dissimilarity to rat liver ferritin as demonstrated with a common amino acid index test and with immunoelectrophoresis experiments.