Keratin 26, a novel member of the goat type I keratin gene family

Keratins and keratin-associated proteins make up the main structural components of the cashmere fiber. In this study, we constructed a skin cDNA library of Liaoning new-breeding cashmere goat during follicle anagen. A total of 1986 ESTs were sequenced from the skin library and the 1126 unisequences were homologous to functionally characterized or hypothetical proteins, including 14 unisequences that encoded structural proteins of cashmere fiber. We also isolated a full-length cDNA clone, which showed high homology with another known sequences, termed keratin 26 (K26). The K26 protein consisted of 468 amino acids, exhibited a high amount of histidine, lysine and methionine, but low content of arginine, isoleucine and cysteine, and possessed a glycine-rich region. Additionally, K26 contained a relatively high proportion of α-helix structures and showed a close relationship with K25 and K27. RT-PCR analysis showed that K26 were only present in goat skin. The above results point to K26 being a novel cashmere goat keratin family member.