Cloning and Expression of Cellular Glutathione Peroxidase (GPXl) in Japanese Quail {Coturnix japonica)

Glutathione peroxidase 1 (cellular glutathione peroxidase, EC 1.11.1.9 (GPX1)) is an antioxidant enzyme that plays an important role in scavenging reactive oxygen species to protect cells from oxidative damage. To clone the quail GPX1, total RNA was extracted from mature female quail liver. Degenerated primers were designed based on conserved sequences among five species (human, monkey, cattle, rat, and mouse) to amplify the quail fragment GPX1 with reverse transcription polymerase chain reaction. The cDNA sequence of partial Japanese quail GPX1 is 212 nucleotides in length. The rapid amplification of cDNA ends system (5ʹ and 3ʹ RACE) was used to obtain the full-length Japanese quail GPX1 cDNA. The 843-nucleotide quail GPX1 cDNA contains a 153 amino acid open reading frame, a 1 bp /ʹ-untranslated region, and a 377 bp 3ʹ-untranslated region containing the poly A tail. It contains putative selenocysteine residue which is encoded by an unusual stop codon TGA. Comparison of amino acid sequences showed that Japanese quail GPX1 shares 65-14% identity with GPX1 of other animals, suggesting that our clone is an authentic member of GPX1. GPX1 mRNA was expressed in all tissues examined including kidney, adrenal gland, liver, small follicle, small intestine, heart, and breast muscle; the highest level was detected in liver. This quail GPX1 cDNA will provide a tool for further studies of GPX1 expression in the quail.