CYTOKERATIN EXPRESSION IN SIMPLE EPITHELIA .2. CDNA CLONING AND SEQUENCE CHARACTERISTICS OF BOVINE CYTOKERATIN-A (NO-8)
CYTOKERATIN EXPRESSION IN SIMPLE EPITHELIA .2. CDNA CLONING AND SEQUENCE CHARACTERISTICS OF BOVINE CYTOKERATIN-A (NO-8)
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DOI：
10.1111/j.1432-0436.1986.tb00788.x
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发表时间：
1986-01-01
期刊：
影响因子：
2.9
通讯作者：
FRANKE, WW
中科院分区：
文献类型：
--
作者：
MAGIN, TM;JORCANO, JL;FRANKE, WW
细胞角蛋白A（编号8）是一种细胞骨架蛋白（Mr，在牛细胞中约为53，000），它是所有简单上皮细胞的典型蛋白，广泛存在于所有培养的上皮细胞中，与其伴侣细胞角蛋白D一起，是胚胎发生期间表达的第一种细胞角蛋白（该蛋白的同义词是Endo A和TROMA-1抗原）。我们从由牛膀胱尿道炎的poly（A）+-RNA制备的pUC 8 cDNA文库中分离了一个克隆（pKB 81），它含有3 ″非翻译部分和编码羧基末端尾和几乎整个α-RNA的序列。螺旋杆（369个氨基酸）。Northern-blot分析表明，这种细胞角蛋白的mRNA编码是专门合成在各种上皮组织和上皮细胞培养系。这种细胞角蛋白的氨基酸序列，当与其他中间丝（IF）蛋白质的序列相比，表现出较高的和特定的同源性与其他细胞角蛋白的基本（II型）亚家族，这种同源性，但是，仅限于杆部分。富含羟基氨基酸的尾区（. apprx. 35%），在II型细胞角蛋白中是独特的，因为它不表现出三个结构域的细分，特别是缺乏富含甘氨酸的中间结构域。与两栖动物物种非洲爪蟾的相应细胞角蛋白的部分序列的序列比较，表明高度进化保守。牛细胞角蛋白A与人组织多肽抗原（TPA）（一种在临床肿瘤学中用作肿瘤标志物的可溶性血清组分）的已发表序列的高度序列同源性支持TPA是含有人细胞角蛋白8号杆状部分的蛋白水解溶解片段的观点。我们对克隆pKB 81的分析使得首次比较简单的上皮细胞角蛋白与表皮角蛋白和其他IF蛋白成为可能。这表明，在一些重要的分子特征，细胞角蛋白A（第8号）显着不同的表皮成员相同的细胞角蛋白亚家族，可能反映了不同的细胞功能的尾部区域在复层和简单的上皮。
Cytokeratin A (no. 8) is a cytoskeletal protein (Mr, approximately 53,000 in bovine cells) which is typical of all simple epithelia, is widespread in all cultured epithelial cells, and together with its partner cytokeratin D, is the first cytokeratin expressed during embryogenesis (synonyms for this protein are Endo A and TROMA-1 antigen). We isolated a clone (pKB81) from a pUC8 cDNA library prepared from poly(A)+-RNA of bovine bladder urothelium which contains the 3'' nontranslated portion and the sequence coding for the carboxyterminal tail and almost the whole of the .alpha.-helical rod (369 amino acids). Northern-blot analysis showed that the mRNA coding for this cytokeratin is specifically synthesized in various epithelial tissues and in epithelial cell culture lines. The amino acid sequence of this cytokeratin, when compared with the sequences of other intermediate filament (IF) proteins, exhibits a high and specific homology with other cytokeratins of the basic (type II) subfamily; this homology is, however, restricted to the rod portion. The tail region, which is rich in hydroxyamino acids (.apprx. 35%), is unique among the type-II cytokeratins in that it does not exhibit subdivision in three domains, specifically lacking the glycine-rich middle domain. Sequence comparison with a partial sequence of the corresponding cytokeratin of the amphibian species, Xenopus laevis, indicated high evolutionary conservation. The high sequence homology of bovine cytokeratin A with published sequences of human tissue polypeptide antigen (TPA), a soluble serum component used as tumor marker in clinical oncology, supports the view that TPA is a proteolytically solubilized fragment containing the rod portion of human cytokeratin no. 8. Our analysis of clone pKB81 made possible the first comparison of a simple epithelial cytokeratin with epidermal keratins and other IF proteins. This showed that, in some important molecular features, cytokeratin A (no. 8) differs drastically from the epidermal members of the same cytokeratin subfamily, probably reflecting different cellular functions of the tail region in stratified and simple epithelia.