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:25128630). Ubiquitination leads to TER94/VCP 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 l(3)76BDr/LTN1 and Clbn/NEMF. The complex probably also contains TCF25 as well as TER94/VCP and its ubiquitin-binding cofactors. RQC forms a stable complex with 60S ribosomal subunits. Belongs to the LTN1 family.