2.8 Intracellular Vesicular Trafficking 1

Question 1

What are the 3 pathways for vasicular transport?

Answer 1

Secretion (from ER to cell membrane). Endocytosis. Retrieval/Recycling (cell membrane to ER).

Question 2

What is the lipid anatomy?

Answer 2

Sugars,Phosphate, glycerol, and fatty acid tails.

Question 3

What does the lipid composition of membranes help to do?

Answer 3

Determine organelle identity, define membrane curvature, selectively recruit trafficking-related proteins.

Question 4

What are Rab proteins.

Answer 4

Monomeric GTPases

Question 5

What do Rab proteins do?

Answer 5

Their regulation controls the progression of vesicular transport

Question 6

What are the two forms of Rab?

Answer 6

Rab-GTP active and membrane bound. Rab-GDP inactive in cytosol.

Question 7

What does Rab-GTP do?

Answer 7

Serve as scaffolds as connectors to catch and release other proteins (effector proteins) that catalyze or stimulate the processes as we move along

Question 8

Why does Rab-GTP turn to Rab-GDP?

Answer 8

In order to be recycled.

Question 9

What does GDI do?

Answer 9

Keeps Rab-GDP from interacting with membrane and keep it in the GDP formation until its back home.

Question 10

Assembly of a protein coat on the cytosolic side of teh donor compartment membrane does what?

Answer 10

Shapes the budding vesicle and concentrates the cargo.

Question 11

What are the 3 coats?

Answer 11

COPII, COPI, and Clathrin

Question 12

COPII coats vesicles that move cargo from

Answer 12

ER to Golgi (anterograde)

Question 13

COPI coats vesicles that move cargo from

Answer 13

Golgi to ER (retrograde)

Question 14

Clathrin coats vesicles that move cargo from

Answer 14

golgi to endosomes or inward from cell membrane

Question 15

Cant the NPC squeeze in a vesicle?

Answer 15

No

Question 16

What is a good example of gene duplication?

Answer 16

Coat proteins similar features that have diversified.

Question 17

How does the coat form?

Answer 17

Outer layer forms a cage, inner layer proteins interact with the donor plasma membrane. Inner and outer layers form sequentially.

Question 18

How many layers do the coat proteins each have?

Answer 18

COPII has 2. COPI has 1. Clathrin has 2.

Question 19

what stimulates uncoating?

Answer 19

GAP

Question 20

For the coat proteins, what proteins initiate coating?

Answer 20

COPII: Sar1. COPI: Arf1. Clarithin: AP1/Arf1.

Question 21

For the coat proteins, what initiates uncoating?

Answer 21

COPII: Sec23. COPI: ArfGAPs. Clathrin: AP2

Question 22

What 3 things can cargo be?

Answer 22

Soluble, membrane associated, and tethering/fusion machinery

Question 23

Where is the sorting sequences on the coating proteins?

Answer 23

COPII: cytoslic face. COPI: C term. Clathrin: Linear motifs

Question 24

What is the cargo receptor for the coat proteins?

Answer 24

COPII: Sec 24. COPI: Arf 1: Clathrin: various adapter proteins.

Question 25

What can start the budding process?

Answer 25

Gently bending, and actin.

Question 26

What helps the budding process in the coat proteins?

Answer 26

COPII and COPI: coat polymerization. Clathrin: Actin.

Question 27

What does pinching off require?

Answer 27

Protein factors that distort membrane curvature.

Question 28

What proteins are needed for pinching off via the coat proteins?

Answer 28

COPII: Sar 1. COPI: Arf1. Clathrin: Dynamin +Epsin

Question 29

what must vesicles be before they can ride the cytoskeleton to their destinations?

Answer 29

Must be uncoated

Question 30

What energy is required to uncoat the coat proteins?

Answer 30

COPII and COPI: GTP hydrolysis. Clathrin: ATP hydrolysis.

Question 31

What does Dynein and Kinesin do?

Answer 31

Dynein moves vesicles towards the cell membrane. Kinesin moves vesicles toward the nucleus.

Question 32

What proteins do the coat proteins use to move?

Answer 32

COPII: Dynein. COPI: Kinesin and dynein. Clathrin: Kinesin

Question 33

Once vesicles are at their destination, what happens?

Answer 33

We need to capture and fuse.

Question 34

What do the tethering proteins and SNARE proteins do?

Answer 34

Bring vesicles close enough to target membrane for SNARE proteins to interact and initiate fusion.

Question 35

how many SNAREs are there?

Answer 35

2

Question 36

What is another good example of gene duplication?

Answer 36

SNAREs. One SNARE has 2 dif helices and divided into 2 seperate proteins.

Question 37

What is the common structure for SNAREs?

Answer 37

They this 4 helices bundle that is primarily hydrophobic except in the middle.

Question 38

True or False. T snares will usually be Q, V snares will usually be R.

Answer 38

true

Question 39

True or False? Different compartments have different SNARE profiles.

Answer 39

True

Question 40

Once fusion happens via the SNAREs what must happen in order to untagle the SNAREs?

Answer 40

Energy consumption.