Mj. Fietz et al., ANALYSIS OF THE SHEEP TRICHOHYALIN GENE - POTENTIAL STRUCTURAL AND CALCIUM-BINDING ROLES OF TRICHOHYALIN IN THE HAIR FOLLICLE, The Journal of cell biology, 121(4), 1993, pp. 855-865
Trichohyalin is a structural protein that is produced and retained in
the cells of the inner root sheath and medulla of the hair follicle. T
he gene for sheep trichohyalin has been purified and the complete amin
o acid sequence of trichohyalin determined in an attempt to increase t
he understanding of the structure and function of this protein in the
filamentous network of the hardened inner root sheath cells. Sheep tri
chohyalin has a molecular weight of 201,172 and is characterized by th
e presence of a high proportion of glutamate, arginine, glutamine, and
leucine residues, together totaling more than 75% of the amino acids.
Over 65% of trichohyalin consists of two sets of tandem peptide repea
ts which are based on two different consensus sequences. Trichohyalin
is predicted to form an elongated alpha-helical rod structure but does
not contain the sequences required for the formation of intermediate
filaments. The amino terminus of trichohyalin contains two EF hand cal
cium-binding domains indicating that trichohyalin plays more than a st
ructural role within the hair follicle. In situ hybridization studies
have shown that trichohyalin is expressed in the epithelia of the tong
ue, hoof, and rumen as well as in the inner root sheath and medulla of
the hair follicle.