Cloning, sequence and functional analysis of goat ATP-binding cassette transporter G2 (ABCG2)

ATP-binding cassette transporter G2 (ABCG2) gene encodes a protein that has a wide variety of substrates and is responsible for the active secretion of clinically and toxicologically important molecules into milk. Although known in many species, this marks the first time this gene product has been reported in goats. In this study, we cloned and sequenced goat ABCG2 gene complete coding sequence and predicted its putative translated protein structure with implicative functional domains. One six-transmembrane span on C-terminal region and at least one coiled-coil domain on N-terminal were predicted and compared primarily with those of other closely related species. In addition, three conserved cysteines (in positions 595, 606, and 611) were determined toward the C-terminal of goat's ABCG2. Two known functional motifs were identified in goat's protein through comparative studies with other species. The goat ABCG2 relative expression profile revealed that the gene expression was a function of lactation stage and parallel to goat lactation curve.