Lorenzo Alibardi  , Mattia Toni  , 
    Beta-Keratins of Reptilian Scales Share a Central Amino Acid Sequence Termed Core-Box,
    Research Journal of Biological Sciences,
    Volume 2,Issue 3,
    2007,
    Pages 329-339,
    ISSN 1815-8846,
    rjbsci.2007.329.339,
    (https://makhillpublications.co/view-article.php?doi=rjbsci.2007.329.339)
    Abstract: Beta-keratins determine most of mechanical resistance of reptilian scales. The amino acid sequence of these proteins is not known for most reptiles. An antibody directed against a known  20-amino acid sequence (core-box) of avian beta-keratins has been utilized to detect whether this  epitope is also present in reptilian beta-keratins. The epidermis of most tested species (lepidosaurians, tuatara, chelonians andcrocodilians) shows immunoreactivity in the beta-layer.  In immunoblots, specific immunolabeled bands are seen, mainly within 10-25 kDa (beta-keratin  range). Bidimensional gel electrophoresis shows that most beta-keratins are basic proteins and  contain the epitope for the presence of a core-box. The core-box is conserved among reptile and  bird beta-keratins and seems linked to their structural properties in the formation of hard keratin  packets. The only exception is represented by the soft shelled-turtle (Tryonix spiniferus). The  latter species probably lacks the core-box in its beta-keratin and therefore cannot accumulate beta-keratin packets in the corneous layer explaining the softness of its shell. The molecular analysis on some known beta-keratin sequences suggests that the core-box epitope is centrally located in beta-keratins.
    Keywords: Reptiles;epidermis;beta keratins;electrophoresis;immunoblotting;immunocytochemistry