MTBP, or MDM2-binding protein, binds to MDM2. The MDM2 protein, through its interaction with p53, plays an important role in the regulation of the G1 checkpoint of the cell cycle [1]. MTBP promotes MDM2-mediated ubiquitination and degradation of p53 and also MDM2 stabilisation in an MDM2 RING finger-dependent manner [2]. MTBP differentially regulates the E3 ubiquitin ligase activity of MDM2 towards two of its most critical targets (itself and p53) and in doing so significantly contributes to MDM2-dependent p53 homeostasis in unstressed cells [2]. MTBP inhibits cancer cell migration by interacting with a protein involved in cell motility. This motility protein is alpha-actinin-4 (ACTN4) [3]. It is unclear which regions of MTBP interact with which binding-partner. See PF14919, PF14920.

1: A novel cellular protein (MTBP) binds to MDM2 and induces a G1 arrest that is suppressed by MDM2. Boyd MT, Vlatkovic N, Haines DS; J Biol Chem. 2000;275:31883-31890. PMID:10906133

2: Regulation of p53 and MDM2 activity by MTBP. Brady M, Vlatkovic N, Boyd MT; Mol Cell Biol. 2005;25:545-553. PMID:15632057

3: MTBP suppresses cell migration and filopodia formation by inhibiting ACTN4. Agarwal N, Adhikari AS, Iyer SV, Hekmatdoost K, Welch DR, Iwakuma T; Oncogene. 2012; [Epub ahead of print] PMID:22370640