Annotation of Sheep Keratin Intermediate Filament Genes and Their Patterns of Expression

The study identified nine novel sheep keratin intermediate filament (KRT) genes, increasing the known active genes from eight to 17, aligning with the number found in humans. Notably, sheep lacked the KRT37 gene but included the type II KRT87 gene, highlighting species-specific differences. Phylogenetic analysis showed high sequence conservation across sheep, cattle, and human genomes, though differences were noted in the expression zones of six ovine KRT genes compared to human orthologs. Specifically, KRT40, KRT82, and KRT84 were expressed only in the fibre cuticle, while KRT32, KRT35, and KRT85 were found in both the cuticle and fibre cortex. The remaining 11 genes were expressed solely in the cortex. These findings underscored the species-specific expression patterns and their implications for wool and hair development.