Molecular cloning and bioinformatics analysis of MT-IV in the yak

In this study, coding sequence of yak metallothionein (MT-IV) gene was cloned by reverse transcriptasepolymerase chain reaction (RT-PCR) using the gene specific primers YMT-IVSP1 and YMT-IVSP2, and then 2 pairs specific primers were designed for cloning 2 introns of the yak MT-IV by comparing with the human MT-IV gene. The sequence length of MT-IV gene in yak was 2 099 bp (GenBank Accession No.: EU665491), including 3 exons and 2 introns. The coding regions were composed by 189 nucleotides encoding a 62amino acid protein which contained 20 cysteine residues and no aromatic AA. The length of 2 introns were 1 392 bp and 518 bp, respectively. The MT-IV proteins were highly conserved among yak, cattle, sheep, goat, dog, mouse, human and horse, which had a glutamate insertion at position 5 relative to the classical MTI and MTI1 proteins, and also had the conserved motifs of MTs, such as C－X－C,C－C－X－C－C,C－X－X－C. These results indicated that the yak MT-IV had same molecular characteristics with other mammalian species, but it was necessary to study the expression level of the yak MT-IV in stratified squamous epithe1iat.