Lecture 16

Question 1

Name the 3 enzymes required for ubiquitination

Answer 1

E1 - Ubiquitin activating enzyme

E2 - Conjugating enzyme

E3 - Ubiquitin ligase

Question 2

What does ubiquitin activating enzyme do?

Answer 2

Ub conjugated to E1 enzyme in ATP dependent reaction

Question 3

What does conjugating enzyme do?

Answer 3

Ub is transferred to E2, covalently attached

Question 4

Ubiquitin ligase

Answer 4

Ubiquinated E2 binds E3, as does target protein

E2/3 transfer Ub to substrate

Question 5

Process of ubiquitin mediated protein degradation

Answer 5

Ternary complex (E2, E3, substrate) enables transfer of ubiquitin from E2 to substrate

Successive round of ubiquityation labels structures for ubiquitin mediated protein degradation

Polyubiquitylated substrate released and recognised by proteasome - degraded