Identification of two phospholipid hydroperoxide glutathione peroxidase (gpx4) genes in common carp.

The monomeric selenoprotein, phospholipid hydroperoxide glutathione peroxidase (GPx4) is an essential member of the antioxidant defense system. This paper describes the identification of two gpx4 genes (gpx4a and gpx4b) from somatic tissues of common carp (Cyprinus carpio). The two sequences exhibited 78% and 79% identity at the DNA and the predicted protein level, respectively. The gpx4a transcript was detected in all examined tissues of unstressed animals, with the highest level in the liver. The gpx4b expression was low relative to that of gpx4a in the liver, heart, muscle and brain, and was virtually undetected in the kidney. However, in the olfactory lobe gpx4b was expressed at a fairly high level, the ratio gpx4a/gpx4b being approximately 2:1. Cold shock and Cd(2+) exposure influenced the gpx4a expression to only a slight extent, whereas gpx4b was greatly down-regulated following Cd(2+) exposure.