Membrane-associated dense bands

There is considerable evidence that the membrane-associated dense bands serve as the attachment points of actin filaments to the plasma membrane and that they mediate the transmission of force across the membrane. Bundles of actin filaments and intermediate filaments can be seen penetrating the inner surface of the membrane-associated dense bands in electron micrographs (Small 1985, Gabella 1984, Ashton et al 1975, Pease and Molinari 1960). Dense bands are sometimes coupled to each other in adjacent cells with an intercellular gap of 40-60 nm which is occupied by electron dense material, forming attachment plaques. As at- 

Because the actin filaments of smooth muscle cells terminate at points along the entire length of the cell membrane, the transmission of force in smooth muscle cells is diffused along the entire length and width of the cell surface, rather than being concentrated at a few loci within the cell. 

Non-muscle cells transmit mechanical tension generated by the actin cytoskeleton to the extracellular matrix via focal adhesion sites (Ingber 

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