Figure 7. Mechanism for p53 stabilization in response to DNA damage.

Figure 7

Mechanism for p53 stabilization in response to DNA damage. DNA damage activates two related kinases, ATM and ATR. These kinases can phosphorylate p53 directly at serines-15 and -37. ATM has been reported to also phosphorylate MDM2. ATM activates the kinase Chk2, and ATR activates the kinase Chk1. Activated Chk1 and Chk2 phosphorylate p53 at S20. Current models suggest that S20 phosphorylation stabilizes p53 by blocking the interaction between p53 and MDM2, whereas S15 phosphorylation activates p53 by recruiting p300 (or CBP), which acetylate the p53 C terminus.

From: MDM2: RING Finger Protein and Regulator of p53

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