Keratin-associated Protein Genes Research Articles

Quantitative Analysis of Hair Luster in a Novel Ultraviolet-Irradiated Mouse Model.

Hair luster is a key attribute of healthy hair and a crucial aspect of cosmetic appeal, reflecting the overall health and vitality of hair. Despite its significance, the advancement of therapeutic strategies for hair luster enhancement have been limited due to the absence of an effective experimental model. This study aimed to establish a novel animal model to assess hair gloss, employing ultraviolet (UV) irradiation on C57BL/6 mice. Specifically, UVB irradiation was meticulously applied to the shaved skin of these mice, simulating conditions that typically lead to hair luster loss in humans. The regrowth and characteristics of the hair were evaluated using a dual approach: an Investigator's Global Assessment (IGA) scale for subjective assessment and an image-based pixel-count method for objective quantification. These methods provided a comprehensive understanding of the changes in hair quality post-irradiation. To explore the potential reversibility of hair luster changes, oral minoxidil was administered, a treatment known for its effects on hair growth and texture. Further, to gain insights into the underlying biological mechanisms, bulk RNA transcriptomic analysis of skin tissue was conducted. This analysis revealed significant alterations in the expression of keratin-associated protein (KRTAP) genes, suggesting modifications in hair keratin crosslinking due to UV exposure. These changes are crucial in understanding the molecular dynamics affecting hair luster. The development of this new mouse model is a significant advancement in hair care research. It not only facilitates the evaluation of hair luster in a controlled setting but also opens avenues for the research and development of innovative therapeutic strategies. This model holds promise for the formulation of more effective hair care products and treatments, potentially revolutionizing the approach towards managing and enhancing hair luster.

Ovine KRTAP36-2: A New Keratin-Associated Protein Gene Related to Variation in Wool Yield.

Keratin-associated proteins (KAPs) are structural components of wool fibres. High-glycine/tyrosine (HGT)-KAPs are a subset of the KAP family, and their abundance in fibres varies. In this study, we report the discovery of an ovine HGT-KAP gene to which we assigned the name KRTAP36-2. Polymerase chain reaction and single-strand conformation polymorphism (PCR-SSCP) analyses revealed four variants of this gene in a screening population of 170 sheep from a variety of breeds. The DNA sequencing of the variants revealed four single-nucleotide polymorphisms (SNPs) and a dinucleotide deletion. Three of these SNPs were in the coding region, and one of these was non-synonymous and potentially led to the amino acid substitution p.Cys27Gly near the middle of the protein. The remaining SNP was located near the putative TATA box, and the di-nucleotide deletion was near the putative transcription initiation site. The effect of this variation in KRTAP36-2 was investigated in 274 Southdown × Merino lambs that were the progeny of five sires. Variation was only found to be associated with wool yield, that is, the proportion of the greasy fleece that remained as clean fleece upon scouring (expressed as a percentage). This may have some value in increasing wool production.

Ancient lineages of the keratin-associated protein (KRTAP) genes and their co-option in the evolution of the hair follicle

BLAST searches against the human genome showed that of the 93 keratin-associated proteins (KRTAPs) of Homo sapiens, 53 can be linked by sequence similarity to an H. sapiens metallothionein and 16 others can be linked similarly to occludin, while the remaining KRTAPs can themselves be linked to one or other of those 69 directly-linked proteins. The metallothionein-linked KRTAPs comprise the high-sulphur and ultrahigh-sulphur KRTAPs and are larger than the occludin-linked set, which includes the tyrosine- and glycine-containing KRTAPs. KRTAPs linked to metallothionein appeared in increasing numbers as evolution advanced from the deuterostomia, where KRTAP-like proteins with strong sequence similarity to their mammalian congeners were found in a sea anemone and a starfish. Those linked to occludins arose only with the later-evolved mollusca, where a KRTAP homologous with its mammalian congener was found in snails. The presence of antecedents of the mammalian KRTAPs in a starfish, a sea anemone, snails, fish, amphibia, reptiles and birds, all of them animals that lack hair, suggests that some KRTAPs may have a physiological role beyond that of determining the characteristics of hair fibres. We suggest that homologues of these KRTAPs found in non-hairy animals were co-opted by placodes, formed by the ectodysplasin pathway, to produce the first hair-producing cells, the trichocytes of the hair follicles.

Correlation analysis of four KRTAP gene polymorphisms and cashmere fiber diameters in two cashmere goat breeds

Fiber diameter, a quantitative trait, is controlled by minor effect polygenes. Keratin-associated proteins (KRTAPs) are an important part of hair, and their rich polymorphisms facilitate the mining of cashmere trait molecular markers. In this study, Jiangnan and Tibetan cashmere goats were taken as the research object; multiplex PCR and exome sequencing technology were used to identify the exon regional polymorphisms of cashmere goats KRTAP15-1, KRTAP13.1, KRTAP27-1, and KRTAP24-1. The effects of mutation sites on the fiber diameter of cashmere were analyzed by least square method. The results showed that there were 28 mutation sites in the four KRTAP genes in Jiangnan cashmere goats and Tibetan cashmere goat populations. Among them, the KRTAP13.1, KRTAP27-1, and KRTAP24-1 gene polymorphisms were found to be significantly related to the fiber diameter of Jiangnan cashmere goats. The exploration of molecular markers in this study will help to improve the fiber diameter of the down, while the identification of gene polymorphisms will provide original data for the utilization and protection of germplasm resources of cashmere goats.

Genetic variation in the ovine KAP22-1 gene and its effect on wool traits in Egyptian sheep.

The objective of this study was to investigate the genetic polymorphisms in the keratin-associated protein (KAP22-1) gene in Barki (), Rahmani () and Ossimi () as the three major sheep breeds in Egypt. Subsequently, the detected variants were correlated with important wool traits. The traits included greasy fleece weight (GFW, g), staple length (SL, cm), prickle factor (PF, %), medullated fiber (MF, %), fiber diameter (FD, m), crimp percentage (CR, %) and the standard deviation of FD (SD, m), as well as the subjectively assessed traits of kemp score (KS), handle grade (HG), greasy color grade (GCG), bulk grade (BG), luster grade (LG) and staple structure (SST). Animals were genotyped by polymerase chain reaction (PCR) – single strand conformation polymorphism (SSCP). Five SSCP banding patterns representing three different nucleotide variants (A, B and C) were detected. DNA sequencing confirmed three single nucleotide polymorphisms (SNPs). Animal age significantly affected GFW (), SD (), SL (), CR (), KS (), LG () and SST (). Likewise, the breed had a significant effect on all studied traits except HG and BG, which was not significant. Results showed significant associations between the KAP22-1 variants and CR (), SL (), KS () and GCG (). Interestingly, animals with BB genotypes tended to produce more wool yield ( g) with high SL ( cm), CR ( %) and KS (). Results of this study strongly recommend the KAP22-1 gene as a candidate gene for wool production traits in Egyptian sheep, with new useful insights into the visually assessed wool traits. The identified genetic markers may be incorporated into breeding strategies and genetic improvement programs of wool traits in Egyptian sheep.

Identification of the KAP27-1 gene in sheep and its effect on wool traits

ABSTRACT The keratin-associated proteins (KAPs) are structural components of wool and hair fibres, with over 90 genes that encode these proteins having been identified in mammalian species. A KAP gene called KRTAP27-1 was recently identified in goats, but the gene has not been reported in the closely related ruminant species sheep. In this study, we used a polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis to find ovine KRTAP27-1 and investigate nucleotide sequence variation in the gene. Our analysis revealed four sequence variants (named A to D) in 399 New Zealand Merino × Southdown-cross sheep. Within these sequence variants there were five single nucleotide polymorphisms (SNPs) in the coding region, including two non-synonymous SNPs. Six genotypes (AA, AB, AC, BB, BC and BD) of KRTAP27-1 were detected, and for the three genotypes with a frequency of over 5.0%, sheep of genotypes AB and BB produced wool of higher mean staple length (MSL) and higher greasy fleece weight (GFW) than sheep of genotype AA. These results suggest that variation in ovine KRTAP27-1 may be affecting wool growth and thus production.

In silico analysis of promoter region and regulatory elements of sheep keratin-associated protein genes using bioinformatics tools

Keratin-associated proteins (KAPs) are constituents of wool and play an important role in determining the characteristics of wool. Variation in many ovine KAP genes are associated with wool traits and are useful as markers for improving wool traits in sheep. The identification of promoters in a gene is an important part of the recognition of a gene's complete structure. In silico study was done with aim of analyzing the promoter regions and transcription factors with the aid of transcription start site (TSSs), regulatory elements and motifs of sheep KAP genes. Most of predicted TSSs (64%) found below -500 bp away from the start codon of the gene being expressed, and the rest were found from −515 to −1502 upstream of start codon. MKAP3 was identified as the most common motif for sheep KAP genes, which serves as binding sites for Zinc finger transcription factor to regulate the expression of the genes. Poor CpG Islands observed might suggest that their gene expression regulation pattern is tissue specific. In general, in silico analysis of KAP genes of sheep could be helpful to add knowledge about gene regulatory elements in the promoter regions. Furthermore, this finding will help for wool traits improvement of sheep.

Variation in ovine KRTAP8-2 and its association with wool characteristics in Pakistani sheep

The keratin-associated proteins (KAPs) are structural components of wool fibres and variation in genes encoding KAPs may affect wool characteristics. Variation in the KAP gene KRTAP8-2 was investigated in five sheep breeds and crosses in Pakistan. A new sequence of the gene (named variant C) was found, along with the already reported variants A and B. In general linear mixed models (GLMMs) analysing the effect of the presence and absence of these variants on wool traits, the presence of B was found to be associated (P = 0.028) with lower mean staple length (MSL), where the predicted MSL of wool from sheep without B (39.3 ± 8.35 mm) was higher than wool from sheep with B (34.7 ± 9.33 mm). The predicted mean standard deviation of medullation (MeSD) of wool from sheep with variant A (11.2 ± 4.98 %) was lower than wool from sheep without A (32.7 ± 11.80 %), and wool from sheep with B (18.7 ± 8.06 %) had higher predicted MeSDs than wool from sheep without B (10.9 ± 5.06 %). The predicted mean coefficient of variation of medullation (CVMed) of wool from sheep with A (38.6 ± 5.80 %) was lower than wool from sheep without A (88.4 ± 21.21 %), and wool from sheep with B (57.5 ± 12.17 %) had higher predicted CVMed than wool from sheep without B (38.0 ± 6.15 %). In GLMMs analysing genotype differences, the predicted MeSD of wool from sheep of genotype AA (11.1 ± 5.02 %) was lower (P = 0.001) than for wool from sheep of genotype AB (12.9 ± 8.72 %) and BB (33.0 ± 11.88 %), and the CVMed of wool from sheep with genotype AA (37.8 ± 6.17 %) was lower (P < 0.001) than wool from sheep with genotypes AB (43.7 ± 14.23 %) and BB (89.0 ± 21.23 %). Variation in KRTAP8-2 appears to be associated with some important wool traits, but this requires further investigation in more sheep of differing breed.

The Complexity of the Ovine and Caprine Keratin-Associated Protein Genes.

Sheep (Ovis aries) and goats (Capra hircus) have, for more than a millennia, been a source of fibres for human use, be it for use in clothing and furnishings, for insulation, for decorative and ceremonial purposes, or for combinations thereof. While use of these natural fibres has in some respects been superseded by the use of synthetic and plant-based fibres, increased accounting for the carbon and water footprint of these fibres is creating a re-emergence of interest in fibres derived from sheep and goats. The keratin-associated proteins (KAPs) are structural components of wool and hair fibres, where they form a matrix that cross-links with the keratin intermediate filaments (KIFs), the other main structural component of the fibres. Since the first report of a complete KAP protein sequence in the late 1960s, considerable effort has been made to identify the KAP proteins and their genes in mammals, and to ascertain how these genes and proteins control fibre growth and characteristics. This effort is ongoing, with more and more being understood about the structure and function of the genes. This review consolidates that knowledge and suggests future directions for research to further our understanding.

Identification of novel genetic variants for KAP1.1, KAP1.3 and K33 genes in some of indigenous goat breeds of Turkey

The animal fibres such as mohair, cashmere and cashgora have a complex structure and affected by genetic variation of keratin associated protein genes as KAP 1.1 (Keratin Associated Protein 1.1, formerly known as B2A), KAP1.3 (Keratin Associated Protein 1.3, formerly known as B2C) and K33 (Keratin Intermediate Filaments Type I, formerly known as KRT1.2). Keratin-associated proteins play a significant role in identifying structural and mechanical properties of the hair and wool fibres. This study was conducted to detect genetic variation at the KAP1.1, KAP1.3 and K33 genes in indigenous Turkish goat populations using DNA sequencing method. The DNA of 100 individuals selected from 5 different native goat breeds (Hair, Honamlı, Kilis, Norduz, and Angora) that reared different regions of Turkey were used as materials. A total of 59 nucleotide variations and indels (insertion/deletion) of KAP1.1 gene, 15 nucleotide variations and indels of KAP1.3 gene, 16 nucleotide variations of K33 gene were determined in the studied samples. These nucleotide variations and indels have been causing changes in the number and sequence of amino acids. It is necessary to determine the relationships with mohair yield, quality and polymorphisms that are determined in KAP1.1, KAP1.3 and KRT1.2 genes.

Variation in ovine KRTAP8-1 affects mean staple length and opacity of wool fiber

In this study, keratin-associated proteins gene (KRTAP8-1) from five different sheep breeds and breed-crosses (n = 310) was genotyped using a Polymerase Chain Reaction-Single Strand confirmation Polymorphism (PCR-SSCP). Six unique genotypes were observed: AA, AC, AD, AE, DD and EE, with AA being the most common in the different breeds and crosses. Twelve wool characteristics: yield, mean staple length (MSL), bulk, mean fiber diameter (MFD), fiber diameter standard deviation (FDSD), coefficient of variation of fiber diameter (CVFD), medullation, standard deviation of medullation (MeSD), coefficient of variation of medullation (CVMed), opacity, standard deviation of opacity (OpSD), and coefficient of variation of opacity (CVOp) were measured on wool derived from the sheep. Variation in KRTAP8-1 was found to have strong association with MSL, OpSD and CVOp (p ≤ 0.027). The MSL of sheep of genotype AE was greater (p = 0.027) than for sheep of genotype AA. The OpSD of sheep of genotype AA was less (p = 0.017) than sheep with the AE genotype, and the CVOp of sheep with genotype AA was less (p = 0.018) than sheep with genotype AE. Further studies are required to confirm the role of variation in KRTAP8-1 in improving quality wool production.

The effect of androgen on wool follicles and keratin production in Hetian sheep.

To investigate the optimal androgen concentration for culturing Hetian sheep wool follicle and to detect effects of androgen concentration on wool follicle cell proliferation and apoptosis using immunofluorescence labeling and real-time quantitative fluorescence determinations of wool keratin-associated protein gene expression levels. Wool follicles were isolated by microdissection and wool follicles and skin pieces were cultured in various concentrations of dihydrotestosterone (DHT) in culture medium. Next, daily lengthwise growth measurements of wool follicles were obtained using a microscopic micrometer. Cultured Hetian wool follicles were stained using the SACPIC method to reveal wool follicle structure, while sheep skin slices were used to observe cell proliferation by immunostaining and cell apoptosis using the TUNEL method. At the molecular biological level, keratin-associated protein (Kap) gene expression was studied using wool follicles cultured for various numbers of days in vitro. Effects of androgen concentrations on Hetian wool follicle growth and development were experimentally studied. EdU proliferation assays revealed that androgen promoted cell proliferation within wool follicle dermal papillae. TUNEL apoptosis detection demonstrated that androgen treatment could delay cell apoptosis. Quantitative reverse transcription polymerase chain reaction (qPCR) results demonstrated that gene expression level patterns of Hetian mountain sheep super-high sulfur protein. Kap1.1, KIF1.2, Kap2.12 and Kap4.2 gene expression level of the mountainous experimental group was significantly higher than plains Hetian sheep. An androgen concentration of 100 nM can promote the growth of Hetian wool follicle cells in vitro, resulting in overexpression of some genes of the Kap family.

A highly polymorphic caprine keratin-associated protein gene identified and its effect on cashmere traits.

Five keratin-associated protein 6 genes (KRTAP6) have been identified in sheep and variation in some KRTAP6 has been associated with wool fiber diameter-related traits, but none of these homologues have been identified in goats. In this study, we reported the identification of the sheep KRTAP6-5 homologue on goat chromosome 1 and polymerase chain reaction (PCR)-single strand conformation polymorphism analysis in 300 Longdong cashmere goats revealed the existence of 12 variant sequences. Both coding region and 3'UTR of the putative caprine KRTAP6-5 displayed a biggest sequence similarity to ovine KRTAP6-5 gene. This suggested that the gene represents caprine KRTAP6-5 sequences, and these sequences composed 23 genotypes, which was the most polymorphism gene in KRTAPs that have been studied. Among these sequences, 15 nucleotide substitutions and a 24-bp insertion/detection were identified. Variation in goat KRTAP6-5 was associated with variation in mean-fiber diameter, suggesting that KRTAP6-5 is worthy of further study in the context of variation in cashmere traits.

Variation in the Caprine Keratin-Associated Protein 27-1 Gene is Associated with Cashmere Fiber Diameter.

Variation in some caprine keratin-associated protein (KAP) genes has been associated with cashmere fiber traits, but many KAP genes remain unidentified in goats. In this study, we confirm the identification of a KAP27-1 gene (KRTAP27-1) and describe its effect on cashmere traits in 248 Longdong cashmere goats. A polymerase chain reaction–single strand conformation polymorphism (PCR-SSCP) analysis was used to screen for sequence variation in this gene, and three sequence variants (named A to C) were found. These sequences have the highest similarity (77% identity) to a human KRTAP27-1 sequence, while sharing some homology with a predicted caprine KRTAP27-1 sequence ENSCHIG00000023347 in the goat genome construct (ARS1:CM004562.1) at chromosome 1 position 3,966,193–3,973,677 in the forward strand. There were two single nucleotide polymorphisms (SNPs) detected in the coding sequence, including one nonsynonymous SNP (c.413C/T; p.Ala138Val) and one synonymous SNP (c.495C/T). The C variant differed from A and B at c.413C/T, having cytosine in its nucleotide sequence, while the B variant differed from A and C at c.495C/T, having thymine in its nucleotide sequence. Goats of the genotypes AB and BB produced cashmere fibers of higher mean fiber diameter (MFD) than goats of genotype AA, but no difference in MFD was detected between the AB and BB goats. These results suggest that B is associated with increased MFD. Expression of the caprine KRTAP27-1 sequence was predominantly detected in the skin tissue of goats but not or only weakly detected in other tissues, including longissimus dorsi muscle, heart, kidney, liver, lung and spleen.

Variation in the KRTAP6-3 gene and its association with wool characteristics in Pakistani sheep breeds and breed-crosses.

This study investigated variation in the keratin-associated proteins gene, KRTAP6-3, in 5 Pakistani sheep breeds/crosses using polymerase chain reaction-single strand confirmation polymorphism (PCR-SSCP) analysis. Different banding patterns were revealed, including previously described patterns and a novel pattern (named variant H). The amplified PCR product of the novel banding pattern was directly sequenced, and a synonymous nucleotide variation c.51T>C was revealed. Among the wool traits assessed, a strong correlation (r = 0.929; P < 0.001) was observed between fibre diameter standard deviation (FDSD) and coefficient of variation of fibre diameter (CVFD), between FDSD and medullation (r = 0.720; P < 0.001), between FDSD and medullation standard deviation (MeSD) (r = 0.734; P < 0.001), between MeSD and coefficient of variance of medullation (CVMed), (r = 0.903, P < 0.001), and between CVFD and medullation (r= 0.660), CVFD and MeSD (r = 0.786; P < 0.001), CVFD and CVMed (r = 0.701; P < 0.001) and medullation and MeSD (r = 0.771; P < 0.001). Variant B was found to be associated (P = 0.018) with CVFD; the presence of B being associated with a higher CVFD, than in its absence (41.08 ± 3.98 versus 36.34 ± 3.08). Variant C was associated with CVMed (P = 0.040), where sheep with C had a lower CVMed than sheep where it was absent. Variation in KRTAP6-3 was found to affect fibre diameter related traits of wool.

Identification of the Ovine Keratin-Associated Protein 2-1 Gene and Its Sequence Variation in Four Chinese Sheep Breeds.

Keratin-associated proteins are important components of wool fibers. The gene encoding the high-sulfur keratin-associated protein 2-1 has been described in humans, but it has not been described in sheep. A basic local alignment search tool nucleotide search of the Ovine Genome Assembly version 4.0 using a human keratin-associated protein 2-1 gene sequence revealed a 399-base pair open reading frame, which was clustered among nine previously identified keratin-associated protein genes on chromosome 11. Polymerase chain reaction–single strand conformation polymorphism analysis revealed four different banding patterns, with these representing four different sequences (A–D) in Chinese sheep breeds. These sequences had the highest similarity to human keratin-associated protein 2-1 gene, suggesting that they represent variants of ovine keratin-associated protein 2-1 gene. Nine single nucleotide variations were detected in the gene, including one non-synonymous nucleotide substitution. Differences in variant frequencies between fine-wool sheep breeds and coarse-wool sheep breeds were detected. The gene was found to be expressed in various tissues, with the highest expression level in skin, and moderate expression levels in heart and lung tissue. These results reveal that the ovine keratin-associated protein 2-1 gene is variable and suggest the gene might affect variation in mean fiber diameter.

Identification of Caprine KRTAP28-1 and Its Effect on Cashmere Fiber Diameter.

The keratin-associated proteins (KAPs) are constituents of cashmere fibers and variation in many KAP genes (KRTAPs) has been found to be associated with fiber traits. The gene encoding the high-sulphur KAP28-1 has been described in sheep, but it has not been identified in the goat genome. In this study, a 255-bp open reading frame on goat chromosome 1 was identified using a search of similar sequence to ovine KRTAP28-1, and that would if transcribed and translated encode a high sulphur KAP. Based on the analysis of polymerase chain reaction amplicons for the goat nucleotide sequences in 385 Longdong cashmere goats in China, five unique banding patterns were detected using single strand conformation polymorphism analysis. These represented five DNA sequences (named variants A to E) and they had the highest resemblance to KRTAP28-1 sequences from sheep, suggesting A–E are variants of caprine KRTAP28-1. DNA sequencing revealed a 2 or 4-bp deletion and eleven nucleotide sequence differences, including four non-synonymous substitutions. Of the four common variants (A, B, C and D) found in these goats, the presence of variant A was associated with decreased mean fiber diameter and this effect appeared to be additive. These results indicate that caprine KRTAP28-1 variation might have value as a molecular marker for reducing cashmere mean fiber diameter.

Sequence analysis of high glycine-tyrosine keratin-associated proteins (kaps) in magra sheep

Keratin associated proteins (KAPs) are structural components of the wool fibre. The present study was aimed to analyse nucleotide sequence diversity in three high glycine-tyrosine KAPs gene (HGT-KAP) viz. KAP6, KAP7 and KAP8 from Magra sheep known for lustrous wool. This study was conducted to analyse single nucleotide polymorphisms (SNPs) in these three gene sequences. In open reading frame (ORF), SNPs were not located in KAP 6, however in KAP 7, 14 SNPs were located which leads to 5 synonymous and 9 non-synonymous mutations. In KAP 8 gene only one SNP was present in ORF which leads to tyrosine to asparagine amino acid change. In phylogenetic analysis, KAP 6 proteins of Magra sheep were clustered with KAP 6 amino acid sequence of cashmere goats. Most of the SNPs identified were located into 5′ and 3′ untranslated regions. Since 5′ and 3′ untranslated regions play crucial roles in post-transcriptional regulation of gene expression, these SNPs might play some role in lustrous phenotype of the wool.

Polymorphism in the ovine keratin-associated protein gene KRTAP7-1 and its association with wool characteristics.

The keratin-associated proteins (KAPs) are structural components of wool fibers and variation in the genes encoding the KAPs can affect wool traits. In this study, sequence variation in the ovine KAP7-1 gene (KRTAP7-1) was investigated in 222 sheep across 5 different Pakistani breeds and breed crosses. Two previously identified variants (A and B) of the KRTAP7-1 coding sequence were identified. The frequency of the genotypes AA and AB was 76% and 23%, respectively, and that of BB was 1%. The association of sequence variation with various wool traits and measurements included yield (the proportion of greasy fleece weight that is clean fleece), mean staple length (MSL), wool bulk, mean fiber diameter, fiber diameter SD, the coefficient of variation of fiber diameter, medullation, the SD of medullation, the coefficient of variation of medullation, fiber opacity, the SD of opacity, and the coefficient of variation of opacity. Variation in KRTAP7-1 was found to be associated with yield (P = 0.017). The adjusted mean yield of sheep of genotype AA (n = 169) was 79.9 ± 2.72%, while that of genotype AB (n = 51) was 81.9 ± 3.37%. There was also an association between variation in KRTAP7-1 and MSL (P = 0.024), with sheep of genotype AA (n = 169) having an adjusted mean MSL of 47.3 ± 0.57 mm compared with sheep of genotype AB (n = 51, 50.9 ± 0.65 mm). Yield and MSL are both important wool production traits, hence variation in KRTAP7-1 needs to be further investigated in more sheep of differing breed.

Characterisation of an Ovine Keratin Associated Protein (KAP) Gene, Which Would Produce a Protein Rich in Glycine and Tyrosine, but Lacking in Cysteine.

The keratin-associated proteins (KAPs) are structural components of hair/wool fibres. All of the KAPs identified to date contain cysteine, which is thought to form disulphide bonds cross-linking the keratin intermediate filaments. Here, we report the identification of a KAP gene in sheep that would produce a protein that contains a high proportion (63.2 mol%) of glycine and tyrosine, but would not contain any cysteine. This suggests that other forms of intra- and inter-strand interaction may occur with this KAP, such as interactions via ring-stacking and hydrogen-bonding. The gene was dissimilar to any previously reported KAP gene, and was therefore assigned to a new family, and named KRTAP36-1. The KRTAP36-1 genome sequence was almost identical to some EST sequences from sheep and goat skin follicles, suggesting that it is present and expressed in sheep and goats. A BLAST search of the human genome assembly sequence did not reveal any human homologue. Three variant sequences (named A to C) of ovine KRTAP36-1 were identified and four single nucleotide polymorphisms (SNPs) were detected. One SNP was located 32 bp upstream of the coding region, and all of the others were in the coding region and were nonsynonymous. After correcting for potential linkage to the proximal KRTAP20-1, variant B of KRTAP36-1 was found to be associated with increased prickle factor (PF) in wool, suggesting that variation in the gene may have the potential to be used as gene marker for breeding sheep with lower PF.