Plays an important role in cell protection against oxidative stress and cell death acting as oxidative stress sensor (PubMed:16139213, PubMed:16139214, PubMed:20457924). Does not play a role in methylglyoxal detoxification (By similarity). Expressed in testis (at protein level). Expressed at high levels only in the later stages of development. Double knockouts for dj-1beta and dj-1alpha is viable but with reduced male fertility (PubMed:16139213, PubMed:20457924). Double knockouts for dj-1beta and dj-1alpha is more sensitive to chemical agents that induce oxidative stress (PubMed:16139213). Double knockouts for dj-1beta and dj-1alpha shows reduced lifespan and decreased spontaneous movement over time (PubMed:20457924). Double knockouts for dj-1beta and dj-1alpha spermatozoa are morphologically normal but immotile with abnormal vacuoles in the Nebenkern, abnormal mitochondria and aberrant separation of investment cones during sperm individualization (PubMed:20457924).