Mouse double minute 4 human homolog of p53 binding protein
p53 binding protein
p53 BINDING PROTEIN MDM4
p53-binding protein Mdm4
FunctionInhibits p53/TP53- and TP73/p73-mediated cell cycle arrest and apoptosis by binding its transcriptional activation domain. Inhibits degradation of MDM2. Can reverse MDM2-targeted degradation of TP53 while maintaining suppression of TP53 transactivation and apoptotic functions.
Tissue specificityExpressed in all tissues tested with high levels in thymus.
Sequence similaritiesBelongs to the MDM2/MDM4 family. Contains 1 RanBP2-type zinc finger. Contains 1 RING-type zinc finger. Contains 1 SWIB domain.
DomainRegion I is sufficient for binding TP53 and inhibiting its G1 arrest and apoptosis functions. It also binds TP73. Region II contains most of a central acidic region and a putative C4-type zinc finger. The RING finger domain which coordinates two molecules of zinc mediates the heterooligomerization with MDM2.
Post-translational modificationsUbiquitinated. Deubiquitinated by USP2; leading to stabilize it.