Cloning and Sequence Analysis of Glyceraldehyde-3-Phosphate Dehydrogenase Gene in Yak

In order to study the biological function of gapdh gene in yak, and prove whether the gapdh gene was a useful intra- reference gene that can be given an important role in molecular biology research of yak, the cDNA sequence encoding glyceraldehyde-3-phosphate dehydrogenase from yak was cloned by the RT-PCR method using gene specific PCR primers.The sequence results indicated that the cloned cDNA fragment (1,008 bp) contained a 1,002 bp open reading frame, encoding 333 amino acids (AAs) with a molecular mass of 35.753 kDa.The deduced amino acids sequence showed a high level of sequence identity to Bos Taurus (99.70%),Xenopus laevis (94.29%),Homo sapiens (97.01%),Mus musculus (97.90%) and Sus scrofa (98.20%).The expression of yak's gapdh gene in heart, spleen, kidney and brain tissues was also detected; the results showed that the gapdh gene was expressed in all these tissues.Further analysis of yak GAPDH amino acid sequence implied that it contained a complete glyceraldehyde-3-phosphate dehydrogenase active site (ASCTTNCL) which ranged from 148 to 155 amino acid residues.It also contained two conserved domains, a NAD binding domain in its N-terminal and a complete catalytic domain of sugar transport in its C-terminal.The phylogenetic analysis showed that yak and Bos taurus were the closest species.The prediction of secondary structures indicated that GAPDH of yak had a similar secondary structure to other isolated GAPDH.The results of this study suggested that the gapdh gene of yak was similar to other species and could be used as the intra-reference to analyze the expression of other genes in yak.(