Analysis of variation in the ovine ultra-high sulphur keratin-associated protein KAP5-4 gene using PCR-SSCP technique

Keratin-associated proteins (KAPs) are one of the main structural components of the wool fibre. Variation in the KAP genes (KRTAPs) may affect the structure of KAPs and hence wool characteristics. In this study, we used PCR-SSCP to analyse ovine KRTAP5-4, a gene encoding a member of the KAP5 family. Five different PCR-SSCP patterns were detected in the 250 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 at this locus. DNA sequencing revealed that these patterns represent five different DNA sequences. One of the sequences was identical to a published ovine KRTAP5-4 sequence. The remaining four were unique, but shared a high homology with the published ovine KRTAP5-4 sequence, suggesting that these sequences represent allelic variants of KRTAP5-4. There were a total of six SNPs and one length polymorphism in the sequences. Of the five SNPs found in the coding region, four were non-synonymous SNPs and would result in amino acid changes. The length polymorphism would affect the cysteine content of the putative peptide and this along with the SNPs may have an impact on the structure of KAP5-4, and hence affect wool traits.