p53-binding domain found in E3 ubiquitin-protein ligase MDM2 and similar proteins
MDM2, also known as double minute 2 protein (Hdm2), or oncoprotein MDM2, or p53-binding protein, exerts its oncogenic activity predominantly by binding the p53 tumor suppressor and blocking its transcriptional activity. It forms homo-oligomers and displays E3 ubiquitin ligase activity, catalyzing the attachment of ubiquitin to p53 as an essential step in the regulation of its expression levels in cells. Moreover, in response to ribosomal stress, MDM2-mediated p53 ubiquitination and degradation can be inhibited through the interaction with ribosomal proteins L5, L11, and L23. MDM2 also has a p53-independent role in tumorigenesis and cell growth regulation. In addition, it binds interferon (IFN) regulatory factor-2 (IRF-2), an IFN-regulated transcription factor, and mediates its ubiquitination. MDM2 contains an N-terminal p53-binding domain and a C-terminal zinc RING-finger domain conferring E3 ligase activity that is required for ubiquitination and nuclear export of p53. It is also responsible for the hetero-oligomerization of MDM2, which is crucial for the suppression of P53 activity during embryonic development, and the recruitment of E2 ubiquitin-conjugating enzymes. MDM2 also harbors a RanBP2-type zinc finger (zf-RanBP2) domain, as well as a nuclear localization signal (NLS) and a nuclear export signal (NES), near the central acidic region.
Jiyao W et al.(2023). "The conserved domain database in 2023.",