E3 ubiquitin-protein ligase which accepts ubiquitin from an E2 ubiquitin-conjugating enzyme in the form of a thioester and then directly transfers the ubiquitin to targeted substrates (By similarity). Involved in the ubiquitination and proteasomal-mediated degradation of cytoplasmic and mitochondrial proteins (PubMed:24703696, PubMed:21673654). Positively regulates lin-12 activity in the anchor cell (AC)/vulval precursor (VU) cell fate decision (PubMed:25552605). Negatively regulates glp-1 activity in germline proliferation (PubMed:25552605). May play a role in the formation of fibrous organelles, a hemidesmosome-like structure attaching muscles to the epidermis (PubMed:20153198). Regulates germline DNA double-strand-break repair and apoptosis in response to DNA damage by recruiting E4 ubiquitin-protein ligase ufd-2 to DNA repair foci (PubMed:27669035). 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. Expressed in most tissues, including hypodermis, muscle, intestine, vulva, and neurons. RNAi-mediated knockdown causes no visible phenotype (PubMed:20153198). RNAi-mediated knockdown in a glp-1(ar202) mutant background causes an increase in the number of sterile animals (PubMed:25552605). RNAi-mediated knockdown in a vab-10(e698) mutant background causes 50 percent larval lethality associated with the detachment of muscles from the epidermis (PubMed:20153198). Belongs to the UPL family. K-HECT subfamily.