Question

Which one of the following proteins is often referred to as "the guardian of the genome"?

• A. PFU
• B. Rb
• C. Myc
• D. p53

Hint:

The link between \textbf{p53} and "guardian of the genome" is one of the most famous in molecular cancer biology. Mutations in the TP53 gene (which codes for p53) are found in over 50\% of all human cancers, highlighting its critical role.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The title "guardian of the genome" is a well-known epithet for a specific tumor suppressor protein that plays a central role in maintaining genetic stability and preventing cancer.
Step 2: Detailed Explanation:


The protein p53 is a transcription factor that is activated in response to various cellular stresses, most importantly, DNA damage.

Once activated, p53 can halt the cell cycle (cell cycle arrest) to allow time for DNA repair.

If the DNA damage is too severe to be repaired, p53 will trigger apoptosis (programmed cell death), eliminating the potentially cancerous cell.

By preventing cells with damaged DNA from proliferating, p53 maintains the integrity of the genome and suppresses tumor formation. This critical role has earned it the nickname "the guardian of the genome."

The other options are different types of proteins: Rb is another tumor suppressor that controls the G1/S checkpoint. Myc is a proto-oncogene that promotes cell proliferation. PFU stands for "plaque-forming unit" and is a measure used in virology, not a protein name in this context.

Step 3: Final Answer:
The protein p53 is referred to as "the guardian of the genome."