Characterization and expression analysis of the hair keratin associated protein KAP26.1

Background Human hair follicle keratin-associated proteins (KAPs) comprise a large multigene family of proteins thought to be responsible for the bundling of keratin intermediate filaments. Recently, four new KAP family members KAP24.1, KAP25.1, KAP26.1 and KAP27.1 were identified from the genome, but the expression of only one, KAP24.1, was investigated and shown in hair follicles. Objectives In the current study, the expression of the remaining members of the family were analysed. Methods Reverse transcriptase-polymerase chain reaction analysis of samples from numerous human organs was used. Results Only KAP26.1 showed expression, which was limited to the hair follicle. By in situ hybridization and immunohistochemistry using a specific antiserum, KAP26.1 was localized to the differentiated portion of the hair cuticle. Conclusions As well as KAP24.1 in hair follicles, expression of KAP26.1 was shown and is found in the differentiated part of the hair cuticle.