Keratin intermediate filaments (KIFs) and keratin associated proteins (KAPs) are the predominant protein classes of hair and wool (1, 2, 3). Three breeds of sheep which produce wool with contrasting characteristics, New Zealand Wiltshire, Romney and Merino sheep, were used to investigate the relationships between keratin gene expression and fibre traits. Ten genes which encode three KIFs (K31, K38 and K85), four high sulphur proteins (KAP1.1, KAP1.2, KAP1.3 and KAP1.4), one ultra-high sulphur protein (KAP4.3) and two high glycine-tyrosine proteins (KAP6.1 and KAP8.1), were examined as representative of the major keratin protein classes using quantitative RT-PCR. Significant breed differences were detected in the expression of seven of these genes in skin. While the expression levels of some genes were weakly correlated with individual fibre traits, high correlations were found between an index derived from the relative abundance of all 10 genes and single or multiple fibre traits. These results suggested that, collectively, the relative abundance of KIFs and KAPs underlie the development of the physical properties of the wool fibre. Data on the quantitative and spatial expression of KIF and KAP genes and wool fibre traits could be developed as tools for predicting fibre attributes. Ongoing progress in elucidating KIF and KAP genomic variation in sheep, and their association with different fibre phenotypes, will permit accelerated genetic selection of sheep with improved or novel wool properties.

References:
1. Langbein, L., and Schweizer, J. (2005) Int Rev Cytol 243:1-78.
2. Rogers, et al (2006) Int Rev Cytol 251:209-263.
3. Powell B.C., and Rogers, G.E. (1997) Formation and Structure of Human Hair. Birkhauser Verlag, Basel, Switzerland, pp. 59-148.