Trichohyalin (TCHH)

Trichohyalin confers mechanical strength to the hair follicle inner root sheath and to other toughened epithelial tissues, such as the hard palate and filiform ridges of the tongue, by forming multiple complex crosslinks with itself and with other structural proteins.The predicted protein sequence consists of full and partial repeats of a 23-amino acid sequence that could form an alpha-helical rod, followed by a C-terminal domain.

In situ hybridization of sheep wool follicles showed that trichohyalin was expressed in both the inner root sheath and medulla cells. It was also expressed in the ventral matrix of human nail, with weaker staining of the nail plate, but no staining of the nail bed. Trichohyalin partially colocalized with filaggrin (FLG) in human tongue epithelium.