Keratins are ubiquitous proteins, being found in everything from hair, nails or rhino horn to the nuclei of cells. Because of difficulties relating to extractability, particularly from biological samples, such as hair and wool, extensive sequence homology and the presence of multiple species on gels due to post-translational modifications, keratins present a challenge for analysis using proteomic approaches. Fortunately, thanks to the advent of modern technologies, such as mass spectrometry and immunochemistry there are now a wide range of tools available to aid the detection and identification of these proteins.
To some extent keratin proteins have been neglected because cytosolic proteins are more easily analysed. Nevertheless there are potential benefits from the application of proteomics to the identification and classification of this class of proteins. Studies conducted over the past few years have revealed potential applications for determination of marker proteins for wool quality traits, or as diagnostic tools for the detection of such ailments as cancer and cystic fibrosis or the degradation of lens tissue by ultraviolet light.