L13 KERATIN ASSOCIATED PROTEIN (KAP) GENES OF THE HAIR FIBRE CUTICLE, AND A SUMMARY OF KAP GENES IN HUMANS
Rogers MA1, Langbein L2, Winter H1, Schweizer J1
Section of Normal and Neoplastic Epidermal Differentiation1 and Division of Cell Biology2, German Cancer Research Center, Heidelberg, Germany

The recent completion of the human genome DNA sequence has allowed the bioinformatic identification of four domains of high/ ultrahigh-sulfur keratin associated protein (KAP) genes on chromosomes 17q21.2, 21q22.3, 11p15.5 and 11q13.4, as well as an additional mixed domain of high/ultrahigh sulfur- and high glycine-tyrosine KAP genes on 21q22.1. This evaluation in humans, as well as in mice, has resulted in the identification of ca. 87 KAP genes which have been divided into 23 families; 15 human high/ultrahigh sulfur- and 7 human high glycine-tyrosine KAP genes, as well as one additional, mouse specific, KAP family. Previous reports have described the isolation and characterization of cDNA sequences for the 17q21.2 and 21q22.1 domains and have shown mRNA expression for a majority of these genes via in situ hybridization. This report evaluates the remaining KAP domains on chromosome 21q22.3, 11p15.5 and 11q13.4. The 21q22.3 domain contains 16 KAP genes and 2 KAP pseudogenes. Based on amino acid homology analysis of the encoded proteins, these genes could be divided into 12 KAP 10- and four KAP12 family members. cDNA sequences were isolated for a majority of these genes. The chromosome 11p15.5 and 11q13.4 domains contain a total of 12 KAP genes, 6 on each domain, as well as a single KAP pseudogene on 11q13.4. The genes on both domains are members of the KAP5 family and cDNA sequences for over half of the KAP 5 members have been isolated. In situ hybridization studies in plucked human beard follicles for the KAP5, KAP10 and KAP12 family members have shown nearly identical expression for all of the family members which is localized to a specific region of the hair fiber cuticle, initiating ca. 20-25 cell layers above the apex of the dermal papilla. We believe that this current study, coupled with previously reported data, identifies the total number of high/ ultrahigh sulfur and high glycine-tyrosine hair KAP genes in humans using current bioinformatic means.