Question

DNA damage activates ATM/R which phosphorylates __ to prevent MDM2 binding and increase specific DNA binding.

a) p53
b) Cyclin
c) RB
d) DNA polymerase

Answer 1

DNA damage activates ATM/R which phosphorylates p53, preventing MDM2 binding and thus stabilizing p53 to enhance DNA repair or trigger apoptosis.

Step-by-step explanation:

When DNA damage occurs, it activates ATM/R which then phosphorylates the p53 protein. This phosphorylation is crucial as it prevents MDM2 from binding to p53, allowing p53 to increase its specific DNA binding capacity. This leads to the activation of genes encoding proteins needed for DNA repair and proteins required for apoptosis if repair efforts fail. A key outcome of this process is the prevention of MDM2-mediated p53 degradation, thus stabilizing p53 which is essential in cell cycle arrest, DNA repair, and, if necessary, triggering apoptosis to avoid the replication of damaged DNA.