ABSTRACT
The gene encoding "phospholipid hydroperoxide glutathione peroxidase" (PHGPx), glutathione peroxidase 4 (GPx4), has been initially described as a complex 7 exons-containing gene, yielding a product of 170 amino acids. Some parts of the PHGPx primary structure proved to be similar to glutathione peroxidase 1 (GPx1). Divergent strings of amino acids included large gaps in the PHGPx sequence, in regions corresponding to the subunit interaction sites in bovine GPx1, thus giving an account for the monomeric nature of PHGPx. The evidence that PHGPx is a major protein of mitochondrial capsule of spermatozoa, was a milestone achievement. However, the enzyme was inactive and only high concentrations of thiols, in the presence of guanidine, could regenerate the activity. The double, vital and structural, role of PHGPx in testicular cells was further confirmed by H. Imai, showing that targeted deletion of the entire GPx4 in spermatocytes but not in spermatogonia or somatic cells induces death of the haploid spermatocytes where GPx4 is knocked out.
