The proteome of the wool cuticle

The cuticle is responsible for important wool fiber characteristics such as handle and abrasion resistance, which impact on the fiber's performance in both interior and apparel textiles. The cuticle proteome, however, is not well understood due to the difficulty in isolating pure wool cuticle and its significant resistance to protein extraction, which is attributed to the presence of extensive disulfide and isopeptide cross-linking. We investigated the proteome of highly pure Merino wool cuticle using a combined strategy of chemical and enzymatic digestion and identified 108 proteins, including proteins responsible for a variety of cellular processes. The majority of identified proteins belonged to keratin and nonkeratin protein families known to play an important role in molecular assembly and cellular structure. Keratin-associated, intermediate filament and cytoskeletal keratin proteins were identified as the most prominent keratinous cuticular constituents, while histones, tubulins, and desmosomes were the key nonkeratin structural proteins. We conclude that a variety of proteins contribute to cuticle structure and fiber characteristics, and that the keratinous protein families of IFPs and KAPs represent the most important cuticular constituents.