Lee L D, Kubilus J, Baden H P
Biochem J. 1979 Jan 1;177(1):187-96. doi: 10.1042/bj1770187.
The alpha-keratins, the principal components of the tonafilaments, were extracted, characterized and compared in bovine hoof and snout epidermis. The alpha-fibrous proteins of these tissues are similar with respect to their molecular weights, amino acid composition and percentage of helical structure. However, distinct differences in the polypeptides comprising these proteins were observed. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of these proteins consistently showed that the polypeptide chain in snout, designated as band B (mol.wt. 67,000), was completely absent from hoof preparations. This was confirmed with several alternative preparative procedures. The peptides produced by digestion of the intact keratins from hoof and snout with CNBr were distinctly different. Finally, digestion of keratins from hoof and snout with trypsin yielded products that differed in size and resistance to further digestion. Thus, in addition to the interspecies polypeptide heterogeneity documented in the literature, this report establishes the intraspecies heterogeneity of keratins and suggests that these differences are due to either the expression of different gene products or differences in post-translational modifications in these two tissues.
在牛蹄和口鼻部表皮中提取、表征并比较了作为张力细丝主要成分的α - 角蛋白。这些组织的α - 纤维蛋白在分子量、氨基酸组成和螺旋结构百分比方面相似。然而，观察到构成这些蛋白质的多肽存在明显差异。对这些蛋白质进行十二烷基硫酸钠/聚丙烯酰胺凝胶电泳时，始终显示口鼻部的多肽链（命名为B带，分子量67,000）在蹄部制剂中完全不存在。这通过几种替代制备程序得到了证实。用溴化氰消化蹄部和口鼻部完整角蛋白产生的肽明显不同。最后，用胰蛋白酶消化蹄部和口鼻部角蛋白产生的产物在大小和对进一步消化的抗性方面存在差异。因此，除了文献中记载的种间多肽异质性外，本报告还确立了角蛋白的种内异质性，并表明这些差异是由于这两种组织中不同基因产物的表达或翻译后修饰的差异所致。
