DAXX helical bundle (DHB) domain / Rassf1C complex
[Q5TZT2_HUMAN] Potential tumor suppressor. Required for death receptor-dependent apoptosis. Mediates activation of STK3/MST2 and STK4/MST1 during Fas-induced apoptosis by preventing their dephosphorylation. When associated with MOAP1, promotes BAX conformational change and translocation to mitochondrial membranes in response to TNF and TNFSF10 stimulation. Isoform A interacts with CDC20, an activator of the anaphase-promoting complex, APC, resulting in the inhibition of APC activity and mitotic progression. Inhibits proliferation by negatively regulating cell cycle progression at the level of G1/S-phase transition by regulating accumulation of cyclin D1 protein. Isoform C has been shown not to perform these roles, no function has been identified for this isoform. Isoform A disrupts interactions among MDM2, DAXX and USP7, thus contributing to the efficient activation of TP53 by promoting MDM2 self-ubiquitination in cell-cycle checkpoint control in response to DNA damage.        
Publication Abstract from PubMed
DAXX is a scaffold protein with diverse roles including transcription and cell cycle regulation. Using NMR spectroscopy, we demonstrate that the C-terminal half of DAXX is intrinsically disordered, whereas a folded domain is present near its N terminus. This domain forms a left-handed four-helix bundle (H1, H2, H4, H5). However, due to a crossover helix (H3), this topology differs from that of the Sin3 PAH domain, which to date has been used as a model for DAXX. The N-terminal residues of the tumor suppressor Rassf1C fold into an amphipathic alpha helix upon binding this DAXX domain via a shallow cleft along the flexible helices H2 and H5 (K(D) approximately 60 muM). Based on a proposed DAXX recognition motif as hydrophobic residues preceded by negatively charged groups, we found that peptide models of p53 and Mdm2 also bound the helical bundle. These data provide a structural foundation for understanding the diverse functions of DAXX.
Structural Characterization of the DAXX N-Terminal Helical Bundle Domain and Its Complex with Rassf1C.,Escobar-Cabrera E, Lau DK, Giovinazzi S, Ishov AM, McIntosh LP Structure. 2010 Dec 8;18(12):1642-53. PMID:21134643
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.