E3 ubiquitin-protein ligase. Component of the ribosome quality control complex (RQC), a ribosome-associated complex that mediates ubiquitination and extraction of incompletely synthesized nascent chains for proteasomal degradation (PubMed:23685075, PubMed:25132172, PubMed:25578875, PubMed:28757607). Ubiquitination leads to VCP/p97 recruitment for extraction and degradation of the incomplete translation product (By similarity). S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. Component of the ribosome quality control complex (RQC), composed of at least the E3 ubiquitin ligase LTN1 and NEMF associated with the 60S ribosomal subunit (PubMed:25578875). The complex probably also contains TCF25 as well as VCP/p97 and its ubiquitin-binding cofactors (By similarity). Autoubiquitinated. Belongs to the LTN1 family. Contaminating sequence. Potential poly-A sequence. Extended N-terminus. Truncated N-terminus.