Mdm2 p53 Binding Protein Binding Protein (MTBP)

The MDM2 gene is a transcriptional target of p53 and encodes a protein product that is a critical negative regulator of p53 function. The Mtbp protein shares 38% overall sequence identity with 2 S. cerevisiae proteins, Boi1p and Boi2p, which are known to inhibit growth when expressed at high levels. The interaction between Mtbp and Mdm2 requires the C-terminal portion of Mtbp and the N-terminal portion of Mdm2.

Northern blot analysis detected expression of Mtbp in a wide variety of tissues, with highest expression in thymus, testis, and ovary. expression of the Mtbp protein at high levels leads to p53-independent G1 arrest that can be suppressed by Mdm2. The authors proposed the MTBP is a growth regulator and may encode a novel tumor suppressor protein.