Desmosomes plaques

Desmoplakin is the most abundant desmosomal component that plays a critical role in linking intermediate filament networks to the desmosomal plaque. Desmoplakin forms rod-like dimers that bind to intermediate filaments and to the cadherin-associated proteins plakoglobin and plakophilin. Gene knock-out experiments have revealed an essential role of desmoplakin in establishing cell-cell contacts in early mouse embryos. 

Bornslaeger, E. B., Corcoran, C. M., Stappenbeck, T. S., and Green, K. J. (1996). Breaking the connection Displacement of the desmosomal plaque protein desmo-plakin from cell-cell interfaces disrupts anchorage of intermediate filament bundles and alters intercellular junction assembly./. Biol. Chem. 134, 985-1002. 

Kapprell, H.-P., Owaribe, K., and Franke, W. W. (1988). Identification of a basic protein of Mr 75,000 as an accessory desmosomal plaque protein in stratified and complex epithelia. / Biol. Chem. 106, 1679-1691. 

Franke WW, Moll R, Mueller H, et al. Immunocytochemical identification of epithelium-derived human tumors with antibodies to desmosomal plaque proteins. Proc Natl Acad Sci USA. 1983 80 543-547. 

Desmoplakins I and n are key plaque proteins which anchor desmosomes to keratin filaments in the epidermis. Desmosomes are critical adhesion complexes between adjacent epithelial cells, that assemble in response to cell-cell contact and raised levels of extracellular Ca2+ (Green and Gaudry, 2000). SERCA2 and desmoplakins have been shown to interact in a Ca2+ dependent manner on the ER membrane in cultured human primary keratinocytes, suggesting that SERCA2 may have an accessory function in desmosomal assembly (Dhitavat et al., 2003a). 

Desmosomes are intercellular junctions, consisting of two cell membranes, separated by an interspace. The interspace contains dense fibrillar plaques rich in cell adhesion proteins of the cadherin type. Desmosomes are important for cell-cell adhesion and communication. Epithelial tissue in the body stretched mechanically is rich on desmosomes. 

The desmosomal junction is a morphological entity that is very distinct from adherence junctions involving classical cadherins [44]. The plasma membrane domains of apposing cells are separated by a 20-30 nm thick layer, which in cross section in electron micrographs reveals a midline structure and electron-dense threads stretching laterally from the midline back to the plasma membrane. The cytoplasmic face of each membrane domain is covered with an electron-dense plaque to which bundles of intermediate filaments attach, rather than the actin filaments present in adherence junctions containing classical cadherins. In most epithelia the intermediate filaments are based on keratins but rarer examples of desmosomal junctions coupled into intermediate filaments of the vimentin or desmin type are known [5]. 

Anchoring junctions may link cellular cytoskeleton proteins through the plasma membrane to the extracellular matrix or an adjacent cell. Such an anchoring junction involves a transmembrane protein that binds the cytoskeleton on the cytoplasmic face of the plasma membrane. On the extracellular face of the plasma membrane, the anchoring junction binds either the extracellular matrix (focal contacts, adhesion plaques, or hemidesmosomes) or a receptor on another cell (adhesion belt or desmosomes). 

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