The Fate of Trichohyalin

Trichohyalin (THH) was identified as a major structural protein in hair follicle cells, undergoing postsynthetic modifications by Ca²⁺-dependent enzymes, transglutaminases (TGases), and peptidyl-arginine deiminase. The study explored the processing of a truncated, more soluble form of THH (THH-8) in vitro, finding that TGase 3 had the highest kinetic efficiency for cross-linking THH-8. The data suggested an in vivo model where THH is first denatured by peptidyl-arginine deiminase, making it more soluble and available for efficient cross-linking by TGase 3, forming rigid structures in hair follicle cells. This sequence was supported by the expression timing of THH and TGase 3 in hair follicle cells.