Inner root sheath

The head and tail domains in keratin molecules generally contain a multitude of sites that allow keratin IFs to form covalent bonds with other proteins. For example, in the case of the keratin IFs in the inner root sheath, lysine to glutamine crosslinks have been characterized between the head and (more often) the tail domains in (generally) both Type I and Type II chains, envoplakin, epiplakin, the SPR2 (small proline-rich) family, and trichohyalin (Steinert et al., 2003). Likewise, in noninner root... 

Steinert, P. M., Parry, D. A. D., and Marekov, L. N. (2003). Trichohyalin mechanically strengthens the hair follicle Multiple cross-bridging roles in the inner root sheath. J. Biol. Chem. 278, 41409-41419. 

Amino acid SCMKA SCMKB Free amino acids in wool roots Inner root sheath protein... 

Inner root sheath proteins have been obtained from tissue dissected from the roots of rat vibrissae and porcupine quills and then extracted with 8 M urea containing iodoacetate and pH 8 buffer. The inner root sheath proteins (Table VI) and those isolated from the medulla of hair or porcupine quill are unusual in containing citrulline in protein combination (Rogers, 1958, 1962 Allen et al, 1964). 

A calcium-dependent transglutaminase existing in the inner root sheath and the medullary cells [186-188] catalyzed the formation of isopeptide bonds. Evidence obtained by Rogers et al. [189] suggests that proteins containing the gJu-lys bond, or, more correctly. 

Surrounded by the inner root sheath, the fiber cells multiply and the constant stream of cell production pushes the fiber cells upward toward the skin surface. As the fiber cells move up the hair folhcle, they begin to differentiate into particular cell types cuticle and cortex. In addition to cuticle and cortex cells, the folhcle also produces a central strand of cells that are loosely organized, forming the medulla in the center of the hair fiber. Eventually, the tip of the fiber penetrates the superficial layers of the epidermis and the mature fiber emerges from the skin surface. In the mature fiber, cells are keratinized and hardened. 

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