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

Abstract

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.

Variation in the Ovine KAP6-3 Gene (KRTAP6-3) Is Associated with Variation in Mean Fibre Diameter-Associated Wool Traits

“…Despite the same length (45 bp) of deletion being described in variant C [ 9 ], the deletion identified in variant G appears to be novel and located at a different position ( Figure 2 ). Deletions/insertions that maintain the reading frame have been reported for other ovine KRTAPs , such as KRTAP1-1 [ 20 ], KRTAP5-4 [ 21 ], and KRTAP 6-1 [ 10 ]. The identification of this new deletion in KRTAP6-3 supports the notion that length variation is a structural hallmark of the KRTAPs [ 10 ].…”

An Updated Nomenclature for Keratin-Associated Proteins (KAPs)

“… 1 HS: ≤30 mol % cysteine; UHS: >30 mol % cysteine; HGT: 35-60 mol % of glycine and tyrosine. 2 Membership is based on the identification of the gene, and not the protein. 3 Numbers after “+” represent pseudogenes, and numbers of family members having genetic variation reported are shown in the brackets. 4 Superscript letters indicate the references from which the genetic information was derived: a 35, b 7, c 29, d 40, e 41, f 42, g 43, h 30, i 44, j 3, k 36, l 4, m 45, n 37, o 26, p 25, q 5, r 23, s 6, t 46, u 38 and v 39. 5 While there are currently only three genes reported in the literature for KAP1, there are four known protein sequences. 6 No ovine genes have been identified, despite three protein sequences having been reported 10,47.…”

“…4 Superscript letters indicate the references from which the genetic information was derived: a 35, b 7, c 29, d 40, e 41, f 42, g 43, h 30, i 44, j 3, k 36, l 4, m 45, n 37, o 26, p 25, q 5, r 23, s 6, t 46, u 38 and v 39.…”

“…In sheep, genetic variation has been reported for the KRTAP1 3,4,36, KRTAP3 (37, KRTAP5 5,37, KRTAP6 6,37, KRTAP7 37,38 and KRTAP8 38,39 families. Up to nine alleles have been reported for KRTAP1-3 and KRTAP1-4.…”

Unravelling the proteome of wool: Towards markers of wool quality traits

“…Both for the keratins and KAPs, one of the main problems is the high degree of homology (based on % sequence identity) found within each family, which can be as high as 92% between some members of the Type I keratins and 85% among the Type II keratins. Similar degrees of homology have been also observed for the KAPs and here the situation is further complicated by the existence of polymorphism in some families, notably KAP1.1 [10], KAP1.2 [11], KAP1.3 [12], KAP5.4 [13], KAP7.1, KAP8.1 [14] and KAP11.1 [15]. Nevertheless, studies have provided evidence of distinctive variation of some of these proteins both within and between breeds [16].…”