Keratin 31 (KRT31)

HA1 was expressed in the differentiating cortex of growing (anagen) hair, with expression beginning 2 to 3 cell layers above the apex of the dermal papilla; expression was absent in the inner root sheath and medulla. No HA1 expression was detected during the resting stage (telogen) of the hair cycle.The predicted protein has 416 amino acids, including a 49-amino acid C-terminal domain, and a calculated molecular mass of 47.3 kD. The amino acid sequences of the human and mouse HA1 proteins are 89% identical. Northern blot analysis detected an approximately 1.7-kb HA1 transcript in human scalp but not hairless skin.Approximately 5% of the human population express an acidic 41-kD protein that appears in the electrophoretic pattern of their hair keratins.