Characterization of beta-keratins in lizard epidermis: Electrophoresis, immunocytochemical and in situ-hybridization study

Abstract

Lizard scales are composed of alpha-(cyto-) keratins and beta-keratins. The characterization of the molecular weight and isoelectric point (p I) of alpha- and beta-keratins of lizard epidermis ( Podarcis sicula) has been done by using two-dimensional electrophoresis, immunoblotting, and immunocytochemistry. Antibodies against cytokeratins, against a chicken scale beta-keratin or against lizard beta-keratin bands of 15–16 kDa, have been used to recognize alpha- and beta-keratins. Acid and basic cytokeratins of 42–67 kDa show a p I from 5.0 to 8.9. This indicates the presence of specific keratins for the formation of the stratum corneum. Main protein spots of beta-keratin at 15–17 kDa, and p I at 8.5, 8.2, and 6.7, and one spot at 10 kDa and p I at 7.3 were recognized. Therefore, beta-keratins are mainly basic proteins, and are used for the formation of the hard corneous layer of the epidermis. Ultrastructural immunocytochemistry confirms that beta-keratin is packed into large and dense bundles of beta-keratin cells of lizard epidermis. The use of a probe against a lizard beta-keratin in situ-hybridization studies confirms that the mRNA for beta-keratins is present in beta-cells and is localized around or even associated with beta-keratin filaments.