Polymorphism of the ovine keratin-associated protein 1-4 gene (KRTAP1-4)

Keratin-associated proteins (KAPs) are one of the main structural components of the wool fibre and form a semi-rigid matrix in which the keratin intermediate filaments are embedded. Variation in the KAP genes may affect the structure of KAPs and hence wool characteristics. In this study, we used PCR-SSCP to analyse ovine KRTAP1-4 (previously B2D), a gene encoding a member of the KAP1-x family. Nine different PCR-SSCP patterns were detected in the 320 sheep that were analysed. Either one or a combination of two patterns was observed for each sheep, which was consistent with these sheep being either homozygous or heterozygous for this gene. DNA sequencing revealed that these patterns represent nine different DNA sequences. All of these sequences were unique, but shared a high homology with the published ovine KRTAP1-4 sequence, suggesting that these sequences represent allelic variants of KRTAP1-4. There were a total of 14 single nucleotide polymorphisms (SNPs) identified and these SNPs tended to be clustered in two regions. Of the 13 SNPs found in the coding region, nine were non-synonymous SNPs and would result in amino acid changes. The variation detected here may have an impact on the structure of KAP1-4 and hence affect wool traits.