Molecular Evolution of the Keratin Associated Protein Gene Family in Mammals: Role in the Evolution of Mammalian Hair

The study examined the molecular evolution of the keratin associated protein (KRTAP) gene family, essential for hair formation in mammals. Researchers analyzed KRTAP gene repertoires in eight mammalian genomes, noting an expanded repertoire in rodents and a similar number of genes in humans compared to other primates, despite human hairlessness. New subfamilies of high/ultrahigh cysteine KRTAP genes were identified, evolving through concerted evolution with frequent gene conversion, resulting in higher GC content. In contrast, high glycine-tyrosine KRTAP genes evolved more dynamically with fewer gene conversions and lower GC content, likely due to positive selection. The study concluded that most KRTAP subfamilies emerged early in mammalian evolution, suggesting a diverse KRTAP gene repertoire in mammalian ancestors. Rapid divergent evolution of KRTAPs led to varied hair characteristics among mammals, while concerted evolution homogenized KRTAP subfamilies within species.