p53

Question 1

p53

Answer 1

Activated = stops growth of damaged cells
Protein binds to SV40 virus oncogene
TF induced after cellular damage
-activates genes for inhibiting cellular growth during repair (GIG)
Inhibits cyclin dependent kinases (CDK stimulate cell division)

Question 2

GIG and GSG

Answer 2

Growth interfering genes

Growth stimulating genes (p53 inhibits)

Question 3

p53 inhibits GSG directly

Answer 3

Prevents activator from binding (binds to activator/activator binding site)
Closes chromatin structure

Question 4

p53 inhibits GSG indirectly

Answer 4

Stimulates expression of

• inhibitor protein (p21 inhibits CDK)
• miRNA

Question 5

p53 inhibited by

Answer 5

MDM2 masks its activity region and induces ubiquitinylation
- single ubiquitin = p53 transported to cytoplasm
- >2 = degradation
MDM2 binds to L26 ribosomal protein = reduced p53 translation
Damaged cells proliferate — cancer

Question 6

p53 mechanism of action

Answer 6

p53 activated by DNA damage
It stops cell growth until DNA is repaired
If damage irreparable, p53 acetylated (Lysine 120)
-activates Bax gene —> apoptosis