Keratin 71 (KRT71)

KRT71 belongs to a family of type II keratins that are specifically expressed in the inner root sheath of hair follicles. The deduced 523-amino acid protein has a calculated molecular mass of 57.3 kD. K6IRS1 has a central alpha-helical rod domain and shares approximately 92% amino acid identity with mouse K6irs1. In situ hybridization and indirect immunofluorescence of human hair follicles demonstrated K6IRS1 expression in the Henle and Huxley layers and in the cuticle of the inner root sheath. In all 3 layers, expression of K6IRS1 began above the germinative cell pool and terminated higher up in the follicle with the asynchronous terminal differentiation of each cell layer. K6IRS1 was also detected in the pseudopods of specialized Huxley cells, termed 'Flugelzellen,' which means 'winged cells.'