E3 ubiquitin-protein ligase RNF135

E2-dependent E3 ubiquitin-protein ligase that functions as a RIGI coreceptor in the sensing of viral RNAs in cell cytoplasm and the activation of the antiviral innate immune response. Together with the UBE2D3, UBE2N and UB2V1 E2 ligases, catalyzes the 'Lys-63'-linked polyubiquitination of RIGI oligomerized on viral RNAs, an essential step in the activation of the RIG-I signaling pathway. Through a ubiquitin-independent parallel mechanism, which consists in bridging RIGI filaments forming on longer viral RNAs, further activates the RIG-I signaling pathway. This second mechanism that synergizes with the ubiquitin-dependent one would thereby allow an RNA length-dependent regulation of the RIG-I signaling pathway (Probable). Associated with the E2 ligase UBE2N, also constitutively synthesizes unanchored 'Lys-63'-linked polyubiquitin chains that may also activate the RIG-I signaling pathway.