Immunolocalization of large corneous beta-proteins in the green anole lizard (Anolis carolinensis) suggests that they form filaments that associate to the smaller beta-proteins in the beta-layer of the epidermis.

Abstract

The distribution of large corneous beta-proteins of 18-43 kDa (Ac37, 39, and 40) in the epidermis of the lizard Anolis carolinensis is unknown. This study analyses the localization of these beta-proteins in different body scales during regeneration. Western blot analysis indicates most protein bands at 40-50 kDa suggesting they mix with alpha-keratin of intermediate filament keratin proteins. Ac37 is present in mature alpha-layers of most scales and in beta-cells of the outer scale surface in some scales but is absent in the Oberhäutchen, in the setae and beta-layer of adhesive pads and in mesos cells. In differentiating beta-keratinocytes Ac37 is present over 3-4 nm thick filaments located around the amorphous beta-packets and in alpha-cells, but is scarce in precorneous and corneous layers of the claw. Ac37 forms long filaments and, therefore, resembles alpha-keratins to which it probably associates. Ac39 is seen in the beta-layer of tail and digital scales, in beta-cells of regenerating scales but not in the Oberhäutchen (and adhesive setae) or in beta- and alpha-layers of the other scales. Ac40 is present in the mature beta-layer of most scales and dewlap, in differentiating beta-cells of regenerating scales, but is absent in all the other epidermal layers. The large beta-proteins are accumulated among forming beta-packets of beta-cells and are packed in the beta-corneous material of mature beta-layer. Together alpha-keratins, large beta-proteins form the denser areas of mature beta-layer that may have a different consistence that the electron-paler areas.