E3 ubiquitin-protein ligase that mediates ubiquitination of TP73. Acts to stabilize TP73 and enhance activation of transcription by TP73 (PubMed:12890487). Involved in the regulation of mitotic metaphase/anaphase transition (PubMed:24163370). 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. Interacts with TP73 (PubMed:12890487). Interacts with FZR1 (PubMed:24163370). Predominantly expressed in adult brain, lung and heart. Ubiquitinated and degraded during mitotic exit by APC/C-Cdh1. The disease is caused by variants affecting the gene represented in this entry. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay. Extended N-terminus. Wrong choice of CDS.