A keratin-associated protein (KAP) gene that is associated with variation in cashmere goat fleece weight

Abstract

The keratin-associated proteins (KAPs) are key constituents of cashmere fibres. Of the many mammalian KAP genes (KRTAPs), KRTAP20-1 has been described in humans, but it has not been described in any other species. A search for comparable sequences in the goat genome using the human KRTAP20-1 sequence as a model, revealed an open reading frame on chromosome 1 that would encode a high glycine/tyrosine KAP. Using PCR-single stranded conformational polymorphism (PCR-SSCP) analysis as a screening tool, four different banding patterns were identified in 406 cashmere goats from the Longdong District of the Gansu Province in China. These represented four unique DNA sequences that were named A - D, and six single nucleotide polymorphisms (SNPs) were detected in them. The sequences had highest similarity to the human KRTAP20-1 sequence, and this suggests they are variants of caprine KRTAP20-1. The gene was expressed in secondary fibre follicles, but not in the longissimus dorsi muscle, and tissue from goat heart, liver, lungs and kidneys. Variant A was associated with crimped (un-straightened) fibre length and increased weight of harvested cashmere fibre per goat. Variant B was associated with a reduction in the weight of harvested fibre. Genotype AA goats had a greater harvested fibre weight and crimped fibre length, than genotype BB goats.