P53 Binding Protein Homolog (MDM4) Antibody – Rabbit Polyclonal

This gene encodes a nuclear protein that contains a p53 binding domain at the N-terminus and a RING finger domain at the C-terminus, and shows structural similarity to p53-binding protein MDM2. Both proteins bind the p53 tumor suppressor protein and inhibit its activity, and have been shown to be overexpressed in a variety of human cancers. However, unlike MDM2 which degrades p53, this protein inhibits p53 by binding its transcriptional activation domain. This protein also interacts with MDM2 protein via the RING finger domain, and inhibits the latter's degradation. So this protein can reverse MDM2-targeted degradation of p53, while maintaining suppression of p53 transactivation and apoptotic functions. Alternatively spliced transcript variants encoding different isoforms have been noted for this gene. [provided by RefSeq, Feb 2011]

MDM4: Inhibits 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. Interacts with MDM2, TP53, TP73 and USP2. Found in a trimeric complex with UPB2, MDM2 and MDM4. Interacts (phosphorylated) with YWHAG; negatively regulates MDM4 activity toward TP53. Down-regulated by cisplatin. Expressed in all tissues tested with high levels in thymus. Belongs to the MDM2/MDM4 family. 5 isoforms of the human protein are produced by alternative splicing.

Protein type: Ubiquitin conjugating system; Ligase; EC 6.3.2.-; Ubiquitin ligase

Chromosomal Location of Human Ortholog: 1q32

Cellular Component: nucleoplasm; nucleus

Molecular Function: protein binding; enzyme binding; zinc ion binding

Biological Process: cell proliferation; negative regulation of cell proliferation; G0 to G1 transition; DNA damage response, signal transduction by p53 class mediator; protein stabilization; positive regulation of cell proliferation; protein complex assembly; negative regulation of transcription from RNA polymerase II promoter; negative regulation of protein catabolic process; negative regulation of apoptosis