Search for variation in the ovine KAP7-1 and KAP8-1 genes using polymerase chain reaction-single-stranded conformational polymorphism screening.

Keratins and keratin-associated proteins (KAPs) are large heterogeneous groups of proteins that constitute about 90% of the wool fiber. The genes encoding the high glycine-tyrosine (HGT) KAPs are the first sub-group of KAP genes expressed in the wool follicle and just after expression of the keratin genes. Little is known about variation in these genes, which led us to investigate two HGT-KAP genes, KRTAP7-1 and KRTAP8-1. Polymerase chain reaction-single-stranded conformational polymorphism analysis was used to investigate these genes in 250 Romney-cross sheep. For KRTAP7-1, two unique banding patterns were detected for amplicons that spanned the entire coding region. Sequencing confirmed the presence of two sequences with only one nucleotide difference (c.173G/A) putatively resulting in p.Ser58Asn. One was identical to the published ovine KRTAP7-1 sequence. For KRTAP8-1, five unique banding patterns were detected in an amplicon that spanned the entire coding region. Sequencing revealed five different DNA sequences, all of which were highly homologous to the previously reported ovine KRTAP8-1 sequence. Among these five sequences, four single-nucleotide substitutions were identified and three of them were located in the coding region. One of these was nonsynonymous and would putatively result in p.Tyr34Asn. The variation detected in KRTAP7-1 and KRTAP8-1 may influence their expression or protein structure.