E3 ubiquitin-protein ligase that catalyzes polyubiquitin chains (By similarity). Converts epidermis into cement gland and neural tissue in whole embryos. 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 the cement gland, cranial placodes, and the pronephros. Present as a maternal transcript. Early expression is confined to tissues of ectodermal origin. At stage 16, the predominant area of expression is within the developing cement gland. At stage 27, expression is detected in the anterodorsal lateral line placode, the olfactory placode, and the otic vesicle and pronephros. Auto-ubiquitinated.