Modulates the efficiency of translation termination, resulting in the readthrough of all three types of nonsense codons UAA, UAG and UGA. [E2 ubiquitin-conjugating enzyme]-S-ubiquitinyl-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-N(6)-ubiquitinyl-L-lysine. Interacts with translation release factors eRF1 (SUP45) and eRF3 (SUP35) in vitro. Members of the RBR family are atypical E3 ligases. They interact with the E2 conjugating enzyme UBE2L3 and function like HECT-type E3 enzymes: they bind E2s via the first RING domain, but require an obligate trans-thiolation step during the ubiquitin transfer, requiring a conserved cysteine residue in the second RING domain. Present with 846 molecules/cell in log phase SD medium. Belongs to the RBR family. Lacks the His residue in the RING-type domain 2 that is one of the conserved features of the family.