Molecular cloning, sequence characterization, and gene expression profile of a novel water buffalo (Bubalus bubalis) gene: Na⁺, K⁺-ATPase β₂-subunit (ATP1B2)

Abstract. The Na⁺, K⁺-ATPase is a transmembrane carrier protein which plays an important role in Na-K transport and energy metabolism. The aim of this study was to obtain the full-length coding sequence (CDS) of water buffalo Na⁺, K⁺-ATPase β₂-subunit (ATP1B2) using RT-PCR and to investigate the characterizations of its sequence and tissue expression patterns. Sequence analysis revealed that the CDS of water buffalo ATP1B2 encodes an enzyme of 290 amino acid residues with a deduced molecular weight of 33.39 KDa and a PI of 8.37. Water buffalo ATP1B2 was presumed to have a signal peptide, a strong hydrophobic region and to exert its function in the plasma membrane with high reliability. In addition, water buffalo ATP1B2 has a conserved Na⁺, K⁺-ATPase β domain which belongs to Na⁺, K⁺-ATPase superfamily. The sequence of water buffalo ATP1B2 gene shares 97.6, 97.4, 92.2, 93.2, 89.9, 93.2, 89.5 and 62.9 % identify with its homologous sequence of cattle, sheep, dog, human, mouse, baboon, rat and African clawed frog, respectively. Phylogenetic tree analysis based on the CDS of ATP1B2 gene showed that water buffalo has a closer genetic relationship with cattle than with other species. The ATP1B2 gene was widely expressed in the tissues examined, being high in the pituitary gland and brain, moderate in the muscle, spleen, liver, mammary gland, kidney and rumen, weak in the heart, small intestines and skin, and not expressed in the lung and adipose tissue. This study will establish a foundation for further insights into this novel water buffalo gene.