[Presence and localization of proteins immunologically related to membrane skeletal proteins in human skin].

Recent biochemical studies have shown that spectrin, protein 4.1, and actin form a skeletal protein network that underlines the inner surface of the erythrocyte membrane. The skeleton is a flexible structure that appears to be important in maintaining the shape and mechanical properties of the erythrocyte. Recent studies indicate that immunoanalogues of erythrocyte membrane skeletal proteins and ankyrin (protein 2.1) have been found in a wide variety of non-erythroid tissues. In the present study, in order to examine if human skin contains membrane skeletal proteins, immunochemical analysis was utilized using antibodies against anti-spectrin, anti-beta-fodrin (non-erythroid spectrin), anti-protein 4.1 and anti-ankyrin antibodies. Immunoblot analysis of human epidermis with anti-spectrin and anti-beta-fodrin antibodies revealed that human epidermis contains 240 kDa and 235 kDa spectrin-like proteins, which might be identical to brain fodrin. Human epidermis also contains 4.1-like proteins of 80 kDa and 78 kDa that cross react with anti-protein 4.1 antibodies, and contains ankyrin-like proteins of 210 kDa that cross react with anti-ankyrin antibodies. Analysis with immunofluorescence microscopy revealed that these antibodies reacted along the plasma membranes of human epidermal keratinocytes, eccrine sweat gland cells and sweat ductal cells. These results suggest that a membrane skeletal protein lattice might exist in these cells. Cultured human epidermal keratinocyte in the low Ca2+ medium (0.15 mM) showed that immunoreactive form of protein 4.1 and actin were present diffusely in the cytoplasm. When the cells were cultured with standardized Ca2+ medium (1.85 mM), protein 4.1 and actin were observed linearly along the cell margin and in the cytoplasm. Similar patterns of distribution were observed when anti-beta-fodrin antibody was used. Movement of membrane skeletal proteins from cytosol to the membrane suggest that these proteins or membrane skeletal lattice might play an important role in the formation of intercellular junctions.