Comified cell envelope

Copper-sulfide cluster 884s Coproporphyrin III 843,845s Comified cell envelope 439 Corrin in transmethylation 592 Corrin ring 867, 868 Corrinoid-dependent synthesis of acetyl-CoA 876, 877 Cosmarium 22 COSY-NOESY diagram 143 Cotransport (symport) process 411,416,417 Coulomb 283... 

Candi, E., Tarcsa, E., DiGiovanna,J. J., Compton, J. G., Elias, P. M., Marekov, L. N., and Steinert, P. M. (1998). A highly conserved lysine residue on the head domain of Type II keratins is essential for the attachment of keratin intermediate filaments to the comified cell envelope through isopeptide crosslinking transglutaminases. Proc. Natl. Acad. Sci. USA 95, 2067-2072. 

Steinert, P. M., and Marekov, L. N. (1995). The Proteins elafin, filaggrin, keratin intermediate filaments, loricrin and small proline-rich proteins are isodipeptide cross-linked components of the human epidermal comified cell envelope. /. Biol. Chem. 270, 17702-17711. 

Harding, C.R., et al. 2003. The comified cell envelope An important marker of stratum corneum maturation in healthy and dry skin. Ini J Cosmet Sci 25 157. 

Hohl D, de Viragh PA, Amiguet-Barras F, Gibbs S, Backendorf C, Huber M (1995) The small proline-rich proteins constitute a multigene family of differentially regulated comified cell envelope precursor proteins. J Invest Dermatol 104 902-909... 

Membrane Thickening. Cell envelopes are usually neglected in discussions of skin penetration, although Matoltsy (65) wrote, the cell membrane can be looked on as the specific protective element of each comified cell, since it is much more resistant than the epidermal keratin. He also observed that loss of barrier function is maximum when SC is treated with reagents that aflEect membranes (66). 

DiColandrea, T., Karashima, T., Maatta, A., and Watt, F. M. (2000). Subcellular distribution of envoplakin and periplakin Insights into their role as precursors of the epidermal comified envelope./ Cell Biol. 151, 573-586. 

The stratum comeum is usefully thought of as a brick wall , with the fully differentiated comeocytes comprising the bricks , embedded in the mortar created by the intercellular lipids. A layer of lipid covalently bound to the comified envelope of the comeocyte contributes to this exquisite organization. The intercellular lipids of the stratum comeum include no phosphohpids, comprising an approximately equimolar mixture of ceramides, cholesterol and free fatty acids. These non-polar and somewhat rigid components of the stratum comeum s cement play a critical role in barrier function. On average, there are about 20 cell layers in the stratum comeum, each of which is about 0.5 fim in thickness. Yet, the architecture of the membrane is such that this very thin structure limits, under normal conditions, the passive loss of water across the entire skin surface to only about 250 mL per day, a volume easily replaced in order to maintain homeostasis. 

Unlike the described antagonistic effects of TPA and retinoids on ODC induction, both of these agents induce TG activity in cultured epidermal cells (Yuspa et al., 1980, 1981, 1982). In the case of the phorbol esters, the increased TG activity is associated with induction of differentiation and comified envelope production. Paradoxically, synthesis of comified envelopes is blocked in retinoic acid-treated cells (Yuspa et al., 1982), suggesting that retinoic acid might in some way alter TG activity or possibly modify the substrate for the reaction. 

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