Alibardi Lorenzo, Toni Mattia
Dipartimento di Biologia Evoluzionistica Sperimentale, University of Bologna, Bologna, Italy.
J Exp Zool B Mol Dev Evol. 2006 Nov 15;306(6):528-38. doi: 10.1002/jez.b.21105.
Scales of lizards contain beta-keratin of poorly known composition. In the present study, a rat polyclonal serum against a lizard beta-keratin of 14-15 kDa has been produced and the relative protein has been immunolocalized in the epidermis. The observations for the first time show that the isolated protein band derives from the extraction of a protein component of the beta-keratin filaments of lizard epidermis. In immunoblots and immunocytochemistry, the antiserum recognizes most lizard beta-keratins, but produces a variable cross-reactivity with snake beta-keratins, and weak or no reactivity with beta-keratins isolated from tuatara, turtles, alligator and birds. In bidimensional immunoblots of lizard epidermis, three main spots at 15-16 kDa with isoelectric point at 7.0, 7.6 and 8.0, and an unresolved large spot at 29-30 kDa and with pI at 7.5-8.0, are obtained, may be derived from the aggregation of smaller beta-keratin proteins. The ultrastructural immunolocalization with the antibody against lizard beta-keratin shows that only small and large beta-keratin filaments of beta-cells of lizard epidermis are labeled. Keratin bundles in oberhautchen cells are less immunolabeled. Beta-keratin is rapidly polymerized into beta-packets that merge into larger beta-keratin filaments. No labeling is present over other cell organelles or cell layers of lizard epidermis, and is absent in non-epidermal cells. The antiserum recognizes epitope(s) characteristics for lizard beta-keratins, partially recognized in snakes and absent in non-lepidosaurian species. This result indicates that beta-keratins among different reptilian groups posses different immunoreactive regions.
蜥蜴的鳞片含有成分鲜为人知的β-角蛋白。在本研究中，制备了一种针对14 - 15 kDa蜥蜴β-角蛋白的大鼠多克隆血清，并对相关蛋白进行了表皮免疫定位。这些观察首次表明，分离出的蛋白条带源自蜥蜴表皮β-角蛋白丝的一种蛋白成分的提取。在免疫印迹和免疫细胞化学中，该抗血清识别大多数蜥蜴β-角蛋白，但与蛇β-角蛋白产生可变的交叉反应，与从喙头蜥、龟、短吻鳄和鸟类中分离的β-角蛋白反应较弱或无反应。在蜥蜴表皮的二维免疫印迹中，获得了三个主要斑点，分子量在15 - 16 kDa，等电点分别为7.0、7.6和8.0，以及一个未解析的大斑点，分子量在29 - 30 kDa，等电点在7.5 - 8.0，可能源自较小β-角蛋白的聚集。用抗蜥蜴β-角蛋白抗体进行的超微结构免疫定位表明，仅蜥蜴表皮β细胞的小和大β-角蛋白丝被标记。上表皮细胞中的角蛋白束免疫标记较少。β-角蛋白迅速聚合成β-束，然后合并成更大的β-角蛋白丝。蜥蜴表皮的其他细胞器或细胞层未出现标记，非表皮细胞中也不存在标记。该抗血清识别蜥蜴β-角蛋白的表位特征，在蛇中部分识别，在非鳞龙类物种中不存在。这一结果表明，不同爬行类群中的β-角蛋白具有不同的免疫反应区域。
