The Desmosomal Domain, An Example of Cell-Cell as well as Membrane-Cytoskeleton Interaction
Desmosomes are intercellular junctions characterized by (1) a midline structure containing carbohydrate residues of glycoproteins, (2) the membrane proper, and (3) a cytoplasmic plaque which is insoluble in low and high salt buffers, non-denaturing detergents and thiol agents and is remarkably resistant to treatment with chaotropic and denaturing agents. Major polypeptides of this plaque structure have been characterized by biochemical and both conventional and monoclonal immunological methods. They contain one or two predominant non-glycosylated polypeptides, desmoplakins I (M 250K) and II (M 215K) of almost neutral isoelectric pH, which are closely relateS to each other and have been fairly well conserved in diverse epithelia and during evolution. In addition, at least in epidermis, the plaques contain a non-glycosylated polypeptide of M 83K (“band 5”) isoelectric with serum albumin and non-glycosylated basic polypeptide of M 75K (“band 6”). The latter two polypeptides have been identified as translational products of epidermal mRNA. Guinea pig antibodies and monoclonal murine antibodies to such plaque proteins have detected similar antigens in epithelial, arachnoidal and myocardial cells, including Purkinje fibre cells of the heart, as well as in tumors derived from epithelial cells, notably carcinomas.
KeywordsHigh Salt Buffer Major Polypeptide Plaque Protein Basic Polypeptide Plaque Structure
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