K-200
p53 Ubiquitination Kit
Catalog #: K-200p53 Ubiquitination Kit
Human Recombinant
This kit is designed for the ubiquitination of p53 (SP-450) by Hmd2 (E3-200). The ubiquitinated protein can be detected by Western blot using the p53 monoclonal antibody (A-200) or other commercially available p53 antibodies. This kit can be used as a positive control in studies that monitors the activities of other known or putative E3 ligase enzymes that ubiquitinate p53. Hdm2 (Human double minute 2) is a RING-finger ubiquitin E3 ligase that acts as a major regulator of the tumor suppressor p53 by inhibiting p53-mediated transactivation which leads to deregulated cell proliferation. The E3 ligase activity is confined to the C-terminal domain of Hdm2 and is responsible for the ubiquitination and subsequent proteasomal degradation of p53. The ubiquitinated p53 substrate can also be used to study degradation by the proteasome (E-365) or the removal of ubiquitin chains by specific deubiquitinating enzymes such as USP7 (E-518). All individual kit components are also available for purchase separately.
NOTE: Kit contains reagents sufficient for 10 x 10 μl reactions.
Concentration of components vary with Lot #.
Tumor suppressor protein p53, a nuclear transcription factor, plays an essential role in the regulation of cell cycle and is frequently mutated or inactivated in many cancers. Numerous post-translational modifications modulate p53 activity including phosphorylation, acetylation, methylation and ubiquitination. Since this protein is ubiquitinated, the stability of p53 is highly regulated via the ubiquitin-proteasome pathway (UPP). Hdm2 is an oncogenic ubiquitin E3 ligase that ubiquitinates p53 thereby inhibiting its transcriptional activity and promoting its proteasomal degradation. Although the isolated RING domain is capable of p53 ubiquitination, other regions of the protein including a central acidic domain are also crucial for full E3 ligase activity. Hdm2 also regulates its own intracellular levels by auto-ubiquitination, and can be SUMOylated which decreases auto-ubiquitination activity but increases activity toward p53. Other E3 ligases that promote the proteasome-mediated degradation of p53 include Pirh2, COP1 and p300. USP7 (HAUSP) stabilizes p53 by deubiquitination and induces p53-dependent cell growth repression and apoptosis. In vivo, USP7 also indirectly affects p53 stability by deubiquitinating HDMX, a regulator of HDM2. Additional factors such as p14ARF and MdmX also modulate p53 function via the UPP.
