Variation in the caprine keratin-associated protein 15-1 (KAP15-1) gene affects cashmere fibre diameter.

Mengli Zhao,Shaobin Li,Jiang Hu,Yuzhu Luo,Jon G H Hickford,Zhiyun Hao,Jiqing Wang,Xiu Liu,Huitong Zhou,Hua Gong

doi:10.5194/aab-62-125-2019

Abstract

Keratin-associated proteins (KAPs) are a structural component of cashmere fibre, and variation in some KAP genes (KRTAPs) has been associated with a number of caprine fibre traits. In this study, we report the identification of KRTAP15-1 in goats. Sequence variation in the gene was detected using the polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) technique in 250 Longdong goats, and six variants (named A to F) containing eight single nucleotide polymorphisms (SNPs) were identified. Five of the SNPs were non-synonymous and would lead to putative amino acid changes. Reverse-transcription polymerase chain reaction (RT-PCR) analysis revealed that KRTAP15-1 was expressed in secondary hair follicles but not in heart tissue, liver tissue, lung tissue, kidney tissue or the longissimus dorsi muscle. Despite being rich in cysteine, the caprine KAP15-1 protein possesses a high content of serine and moderate content of glycine and phenylalanine. Association analyses revealed that KRTAP15-1 variant A was associated with decreased mean fibre diameter (MFD), and this effect appeared to be dominant; while variant C was found to be associated with increased MFD, the effect being recessive. The findings suggest that caprine KRTAP15-1 is highly polymorphic and that variation in this gene affects cashmere MFD.

Highlights

Hair and cashmere are produced by the primary and the secondary hair follicles, respectively, of cashmere goats
keratinassociated proteins (KAPs) have a high content of either cysteine or glycine and tyrosine, and based on this content, the proteins can be divided into three broad groups: the high-sulfur (HS) group, which contains less than 30 mol % cysteine; the ultra-highsulfur (UHS) group, which contains more than 30 mol % cysteine, and the high glycine and tyrosine (HGT) group, which has 35 mol %–60 mol % glycine and tyrosine (Gong et al, 2016)
This study reports the identification of caprine KRTAP15-1, and describes its effect on cashmere fibre traits

Summary

Introduction

Hair and cashmere are produced by the primary and the secondary hair follicles, respectively, of cashmere goats. KAPs have a high content of either cysteine or glycine and tyrosine, and based on this content, the proteins can be divided into three broad groups: the high-sulfur (HS) group, which contains less than 30 mol % cysteine; the ultra-highsulfur (UHS) group, which contains more than 30 mol % cysteine, and the high glycine and tyrosine (HGT) group, which has 35 mol %–60 mol % glycine and tyrosine (Gong et al, 2016) Within these groups, the KAPs can be further subdivided into families based on their sequence similarity, and over 100 KAP genes (called KRTAPs) belonging to 27 fam-

Methods

Results

Conclusion