[Isoform 1]: E3 ubiquitin ligase which accepts ubiquitin from specific E2 ubiquitin-conjugating enzymes, and then transfers it to substrates promoting their ubiquitination. Plays a role in the regulation of antiviral responses by promoting the degradation of TRAF3, TLR4 and TLR9. In turn, down-regulates NF-kappa-B and IRF3 activation as well as beta interferon production. Participates also in the regulation of autophagy by ubiquitinating BECN1 leading to its degradation and autophagy inhibition. Plays a role in ARC-dependent synaptic plasticity by mediating ARC ubiquitination resulting in its rapid proteasomal degradation. Plays aso an essential role in spermatogenesis and male fertility. Mechanistically, regulates meiosis by promoting the degradation of PRKACB through the ubiquitin-mediated lysosome pathway. Modulates the gonadotropin-releasing hormone signal pathway by affecting the stability of STAU2 that is required for the microtubule-dependent transport of neuronal RNA from the cell body to the dendrite.; [Isoform 3]: Inhibits TNF and IL-1 mediated activation of NF-kappa-B. Promotes TNF and RIP mediated apoptosis.