Glutathione peroxidase (GPx) is an antioxidant enzyme that protects cells from oxidative damage in the innate immune responses against bacterial infections. GPx is also involved in immune defenses. In this study, we report cloning and characterization of a GPx (designated as MyGPx) coding sequences and promoter from Japanese scallop, Mizuhopecten yessoensis. The full-length 1081 nt MyGPx mRNA contained a 28 nt 5' untranslated region (UTR), a 603 nt open reading frame and a 450 nt 3' UTR containing a polyadenylation signal (AATAAA). Multiple sequence alignment revealed that amino acids essential to enzymatic function of MyGPx proteins were highly conserved. A 1628 nt 5'-flanking sequence of MyGPx was identified by genome walking. Here, several potential transcription factor binding sites were detected in the putative promoter region, and nine single nucleotide polymorphisms (SNPs) were found in the 5' sequence flanking the promoter region. Quantitative Real time PCR (qRT-PCR) was employed to measure GPx mRNA expression in adult tissues and monitor mRNA expression patterns during embryonic development and following stimulation by the bacteria Vibrillo anguillarum. Collectively, the results suggest that MyGPx fulfills an important function during M. yessoensis development and may be an important immune effector in adult molluscs.
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