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中间丝(Intermediate Filaments,IF)是真核细胞内的蛋白性丝状结构,在电镜下其直径为8～10mm,介于微丝与微管之间而得名。它们广泛地分布于各种细胞内,特别是在核周与细胞连接点上,与微丝微管—起构成细胞骨架。中间丝是细胞骨架及细胞成分中最为稳定的部分,当用高、低离了强度溶液或非离子去垢剂溶解细胞蛋白、离心去除后,中间丝仍为不溶部分,易于分离。它由多肽所组成,但各种中间丝多肽的分子量差别极大,从40～200KD不等。近年在细胞生物学中的一项重大成就是阐明了中间丝可分成五大类,一种细胞类型主要含有一种中间丝,如(1)上皮型细胞含有细胞角蛋白(分子量4D～65KD);(2)肌肉型细胞含有结蛋白(51KD);(3)间质型细胞含有波形蛋白(55KD);(4)神经胶质细胞含有胶质纤维酸性蛋白(50KD);(5)神经细胞含有神经微丝蛋白(70、140、210KD)。可见它们在细胞内的分布具有一定的型特异性。进一步研究发现,细胞内的中间丝在细胞恶变时,仍保留其表达能力,因而可用于低分化肿瘤的组织起源的判断,成为组织肿瘤标志物之一,在肿瘤病理学中具有很大的实用价值。
Intermediate Filaments (IF) is a proteinous filamentous structure in eukaryotic cells. Its diameter is 8 ~ 10mm under the electron microscope and is named after the microfilaments and microtubules. They are widely distributed in a variety of cells, especially in the perinuclear and cell junctions, and microfilament microtubules - constitute the cytoskeleton. Intermediate filament is the most stable part of the cytoskeleton and cellular components, when using high and low strength solution or non-ionic detergent to dissolve cellular protein, after centrifugation removed, the intermediate filament is still insoluble, easy to separate. It is composed of peptides, but the molecular weight of various intermediate silk peptides vary greatly, from 40 ~ 200KD range. One of the major achievements in cell biology in recent years is the elucidation of the fact that intermediate filaments can be divided into five major categories, one of which mainly contains an intermediate filament, such as (1) epithelial cells containing cytokeratin (molecular weight 4D to 65KD); (2) muscle-type cells contain desmin (51KD); (3) mesenchymal cells contain vimentin (55KD); (4) glial cells contain glial fibrillary acidic protein (50KD); Neurofilament protein (70, 140, 210 KD). Visible in the distribution of their cells have a certain type specificity. Further study found that the intracellular silk in the cell malignant transformation, still retain its expression capacity, which can be used to determine the origin of tissue differentiation of poorly differentiated tumor tissue markers become one of the tumor pathology has great practical value.