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Essay On Epidermal Keratinization

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The highly regulated process of epidermal keratinization is the result of differential expression of within the epidermis. Basal keratinocytes express intermediate filament keratins 5 and 14. Suprabasal keratinocytes express keratins 1 and 10, which comprises approximately 85% of total proteins found in fully differentiated keratinocytes. Types I & II intermediate filaments (keratins) (Figure 3) are composed of three domains: (1) a central alpha-helical rod domain, (2) an amino-terminal head, and (3) a carboxyl-terminal tail domain both the head and tail globular domains contain end, variable, and homologous subdomains. The central α-helical domain is approximately 330 amino acids long and is divided into four subdomains (1A, 1B, 2A, and …show more content…

Sometimes, an electron dense thin line can be seen underneath hemidesmosomes, outside the cell and adjacent to the plasma membrane. This structure is referred to as the sub-basal dense plate. The hemidesmosome is composed of at least 5 distinict molecules: (1) bullous pemphigoid antigen 1 (BPAG1), (2) plectin, (3) integrins, (4) collagen XVII (BPAG2) (5) CD151. The first two molecules, BPAG1 and plectin, are found within the basal keratinocyte, and have been localized to the inner plaque of the hemidesmosome.[13]
The next two molecules, α6β4 integrin, and collagen XVII extend beyond the basal keratinocyte membrane and into the lamina lucida layer of the basement membrane zone and hence they are known as transmembrane molecules. These latter two molecules can be found within the outer plaque of the hemidesmosome. The last molecule, CD151, the most recently discovered molecule, is closely associated with α6β4 Integrin, and resides at or near the surface of the basal cell plasma membrane. The intermediate filaments attach to BPAG1 and plectin, which compose the hemidesmosome inner plaque. Both plectin and BPAG1 belong to the plakin family of proteins, and share significant sequence homology.[14]
BPAG1 was one of the first hemidesmosomal components identified and has been associated with bullous pemphigoid since the late 1990's. BPAG1 exists in several different isoforms, but it is the 230 kDa

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