Human Hair Keratin-Associated Proteins

Hair keratin-associated proteins (KAP) were identified as crucial components of the hair fiber, forming a strong hair shaft by cross-linking with keratin intermediate filaments. Advances in the study of human KAP led to the characterization of five gene clusters and the identification of over 80 individual KAP genes. In situ hybridization revealed specific expression patterns of KAP genes in different parts of the hair fiber. Additionally, several KAP genes exhibited size polymorphisms due to variable cysteine-rich repeat segments, with distinct patterns observed among different human populations.