2.5. Protein Homeostasis In The Cell

Question 1

Autophagy

Answer 1

Destruction of ‘large’ cytoplasmic contents

Question 2

Proteosome

Answer 2

1. Protein complexes which degrade unneeded or damaged proteins by proteolysis (a chemical reaction that breaks peptide bonds)

Question 3

E1

Answer 3

Ubiquitin-activating enzyme

1. Ubiquitin activates by formation of a bond with E1
2. Requires ATP for energy but is not a phosphorylation reaction

Question 4

E2

Answer 4

Ubiquitin-conjuring enzyme

1. E1 delivers activated ubiquitin to E2

Question 5

E3

Answer 5

E3 ligases
1. Catalyst transfer of ubiquitin from E2 to a lysine in the substrate protein as they provide a specific binding site for the targeted protein