The cDNA-Deduced Amino Acid Sequence for Trichohyalin, a Differentiation Marker in the Hair Follicle, Contains a 23 Amino Acid Repeat

The study identified trichohyalin as a highly expressed protein in the inner root sheath of hair follicles and the hair medulla, serving as an early differentiation marker. A partial cDNA clone for sheep trichohyalin, representing about 40% of the full-length mRNA, was isolated. The encoded carboxy-terminal 458 amino acids included 429 amino acids forming full or partial tandem repeats of a 23 amino acid sequence, rich in charged amino acids. Secondary structure analysis suggested that trichohyalin could form alpha-helical structures, potentially acting as an intermediate filament-associated protein despite lacking the heptad motif necessary for intermediate filament structure.