Collin O, Thomas D, Flifla M, Quintana C, Gouranton J
Laboratoire de Biologie Cellulaire, UA CNRS no. 256, Rennes, France.
Biol Cell. 1988;63(3):297-305.
Crystalline accumulations of ferritin-like particles are present within the cytoplasma 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.
在同翅目沫蝉（Philaenus spumarius）中肠上皮细胞的细胞质和细胞核内存在铁蛋白样颗粒的晶体聚集体。电子显微镜水平的结构研究表明，这些颗粒具有铁蛋白分子的形态特征：晶体具有面心立方结构，晶格参数为14±1纳米；经负染色的分离颗粒具有铁蛋白的外观；在旋转阴影颗粒上可清晰看到3个对称轴；对选定分子进行的图像处理显示出四重对称性。对薄片中微晶聚集体进行的半定量电子微探针分析显示铁/磷原子比很高。经SDS-PAGE分析，该蛋白质亚基的分子量为18,600。就极性和非极性残基而言，该蛋白质的氨基酸组成具有铁蛋白分子的一般特征。但就序列而言，通过共同氨基酸指数测试和免疫电泳实验表明，该蛋白质与大鼠肝脏铁蛋白存在很大差异。
