Knapp B, Rentrop M, Schweizer J, Winter H
J Biol Chem. 1987 Jan 15;262(2):938-45.
We have constructed cDNA libraries with poly(A)+ RNA from normal mouse footpad epidermis and from a squamous cell carcinoma of mouse back skin. Both libraries were screened for type I keratin clones. We present sequence data of three keratin cDNA clones which selected mRNAs coding for two 52-kDa proteins (clones pke 52 and pkSCC 52) as well as for a 50-kDa protein (clone pkSCC50). According to their carboxyl-terminal sequences, the two 52-kDa keratin proteins belong to a group of keratins with serine-rich subdomains adjacent to the alpha-helix, whereas the short carboxyl-terminus of the 50-kDa protein lacks a distinct substructure. Sequentially the two 52-kDa keratins are more closely related to each other than to any other mouse type I keratin. However, in situ hybridization with specific subclones reveals a distinctly different pattern of expression in mouse epithelia. Clone pkSCC 52 contains sequence information for a 52-kDa keratin present in basal cells of epidermis and other stratified epithelia, whereas the pke 52 cDNA encodes a keratin which is predominantly expressed in suprabasal cells of nonepidermal tissues. In terms of nucleotide sequence identities, it cannot precisely be decided which of the two mouse 52-kDa proteins is the equivalent of the human epidermal 50-kDa keratin protein (Hanukoglu, I., and Fuchs, E. (1982) Cell 31, 243-252). In the case of the bovine keratin VII, however (Jorcano, J.L., Rieger, M., Franz, J.K., Schiller, D.L., Moll, R., and Franke, W.W. (1984) J. Mol. Biol. 179, 257-281) the sequence identity values speak for an equivalence with the mouse ke 52 keratin. Obviously, in situ hybridization experiments would best be suited to unravel the precise interspecies relationship between the four highly similar keratins. The discriminatory efficacy of this technique is further emphasized by the demonstration that the mRNA for a 50-kDa keratin is present not only in hyperproliferative epithelia, but also in normal cells of hair follicles.
我们用来自正常小鼠足垫表皮和小鼠背部皮肤鳞状细胞癌的聚腺苷酸加尾RNA构建了cDNA文库。两个文库都进行了I型角蛋白克隆的筛选。我们展示了三个角蛋白cDNA克隆的序列数据，这些克隆选择了编码两种52 kDa蛋白（克隆pke 52和pkSCC 52）以及一种50 kDa蛋白（克隆pkSCC50）的mRNA。根据它们的羧基末端序列，这两种52 kDa角蛋白属于一组在α螺旋附近具有富含丝氨酸亚结构域的角蛋白，而50 kDa蛋白的短羧基末端缺乏明显的亚结构。在序列上，这两种52 kDa角蛋白彼此之间的关系比与任何其他小鼠I型角蛋白的关系更密切。然而，用特定亚克隆进行的原位杂交揭示了在小鼠上皮细胞中明显不同的表达模式。克隆pkSCC 52包含表皮和其他复层上皮基底细胞中存在的一种52 kDa角蛋白的序列信息，而pke 52 cDNA编码一种主要在非表皮组织的基底上层细胞中表达的角蛋白。就核苷酸序列同一性而言，无法精确确定这两种小鼠52 kDa蛋白中的哪一种等同于人类表皮50 kDa角蛋白（Hanukoglu, I., 和Fuchs, E. (1982) Cell 31, 243 - 252）。然而，就牛角蛋白VII而言（Jorcano, J.L., Rieger, M., Franz, J.K., Schiller, D.L., Moll, R., 和Franke, W.W. (1984) J. Mol. Biol. 179, 257 - 281），序列同一性值表明它与小鼠ke 52角蛋白等同。显然，原位杂交实验最适合揭示这四种高度相似的角蛋白之间精确的种间关系。50 kDa角蛋白的mRNA不仅存在于增殖过度的上皮细胞中，也存在于毛囊的正常细胞中，这一证明进一步强调了该技术的鉴别效力。
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