The cell membrane complex: Three related but different cellular cohesion components of mammalian hair fibers

The document reviews the structure, chemistry, and physical properties of the cell membrane complex (CMC) in mammalian hair fibers, emphasizing the differences in the three types of CMC. It builds upon Rogers' initial description of the CMC, presenting new developments that reveal the covalently bound fatty acids of the beta layers are predominantly in the cuticle as monolayers. The beta layers of the cortex are bilayers, attached by ionic and polar linkages to the cortical cell membranes on one side and to the delta layer on the other, but are not covalently bonded. The delta layer, consisting of five sublayers, differs between cortical cells and cuticle cells, with distinct proteins. The cell membranes of cuticle cells are also significantly different from those of cortical cells. The paper presents models with supporting evidence for the three types of CMC: cuticle-cuticle CMC, cuticle-cortex CMC, and cortex-cortex CMC.