Short Communication: molecular characterisation of the wild yak (Bos grunniens mutus) melanocortin receptor-4 (MC4R) gene and a comparative analysis with that of other Bovinae species

Abstract

The wild yak melanocortin-4 receptor (MC4R) gene was cloned and characterised in this study. Results showed that the wild yak MC4R gene was composed of 1343 bp nucleotides with no introns and a GC content of 49%, encoding a polypeptide with 332 amino acids. The speculated size of the open reading frame (ORF) was 999 bp with the start codon – ATG and stop codon – TAA. The sequence of the wild yak MC4R gene in this study is different from that reported before for the domestic yak, and represents a new haplotype within yak species. Nucleotide comparisons of the MC4R gene between wild yak and domestic yak, cattle and zebu showed relatively high sequence conservation. Two nucleotide mutations in the ORF region of the MC4R gene, namely C >T and C >A, existed in both yak species studied here. There were three nucleotide substitutions within the coding region that separated wild and domestic yak from cattle and zebu (A > G, C > G and C > G). One nucleotide mutation detected in the 3′ UTR separated wild yak from cattle and zebu (T > A) (no 3′ flanking region of domestic yak MC4R gene reported). There was no amino acid change between wild yak and domestic yak, or cattle and zebu. However, there were two changes between wild yak and domestic yak compared to cattle and zebu (A to T and V to L). A molecular phylogenetic tree showed wild yak and domestic yak to be joined first, followed by the cattle, zebu and then the sheep (Caprinae). The phylogenetic clustering result was not only identical to the taxonomy, but to the phylogenetic clustering using mitochondrial DNA.