Lecture 15- Vesicular trafficking II

Question 1

What type of experiment can be used to understand the components of COPII vesicles?

Answer 1

Reconstitution experiment

Question 2

What is the basic principle of COPII reconstitution experiment?

Answer 2

ER membrane (containing ribophorin) + cytosol, GTP and ATP leads to the generation COPII vesicles containing p58

Question 3

In reconstitution experiments, what is the cytosol a source of?

Answer 3

COPII coat and adaptor proteins

Question 4

What 2 components to you probe for in a COPII reconstitution experiment?

Answer 4

• Ribophorin in the ER protein

* p58 as a COPII cargo protein

Question 5

What is the consequence of a GDP mutant?

Answer 5

Sequesters GEFs and prevents GEFs from acting

Question 6

What is the consequence of a GTP mutant?

Answer 6

Cannot hydrolyse GTP

Question 7

What do both GTP and GDP mutants have in common?

Answer 7

Can cause a dominant negative effect

Question 8

What does Sar1-GDP expression inhibit?

Answer 8

Inhibits COPII formation

Question 9

What is the GTPase, coat and cargo in COPII vesicle?

Answer 9

GTPase = Sar1
Coat = COPII
Cargo = Newly synthesised proteins

Question 10

What is the GTPase, coat and cargo in a COPI vesicle?

Answer 10

GTPase = Arf1
Coat = COPI
Cargo = Retrieved and newly synthesised proteins

Question 11

What is the GTPase, coat and cargo in a Clathrin (TGN) vesicle?

Answer 11

GTPase = Arf1
Coat = Clathrin
Cargo = Lysosomal protein and regulated secretory proteins

Question 12

What is the GTPase, coat and cargo in clathrin (PM) vesicle?

Answer 12

GTPase = unknown
Coat = clathrin 
Cargo = endocytosed material

Question 13

How does packaging of large cargo occur?

Answer 13

1. The coat is different and more flexible

2. Different interactions between Sec23/24 with the coat accommodates larger cargos