Vesicular Trafficking I

Question 1

In regards to vesicular transport, vesicles __ off from primary compartment and ___ with the next one.

Answer 1

bud; fuse

Question 2

contents of vesicle is called what

Answer 2

cargo

Question 3

Is vesicular transport directional?

Answer 3

yes

Question 4

vesicular transport mediates a ___ exchange of components between various membrane enclosed compartments

Answer 4

continous

Question 5

composition of the membrane and ___ ___ on membrane surface provide cues for incoming traffic

Answer 5

molecular markers

Question 6

combination of markers gives each compartment what?

Answer 6

its full address

Question 7

retrieval pathways do what?

Answer 7

return molecules to source

Question 8

Cells segregate proteins into membrane domains by assembling a special __ on cytosolic side of the membrane

Answer 8

coat

Question 9

When transport vesicles bud off, are they coated or not?

Answer 9

coated

Question 10

What are the 2 functions of the coat on vesicles?

Answer 10

concentrates select proteins in a specialized patch for transport; coat molds the vesicle to form a basket like lattice that deforms the membrane and gives shape to the vesicle

Question 11

When is the vesicular coat discarded?

Answer 11

before vesicle fuses with target membrane

Question 12

COPI and COPII are coats that mediate transport between what two cellular locations?

Answer 12

ER and Golgi

Question 13

Clathrin-coated vesicles mediate transport from what two cellular location?

Answer 13

Golgi and plasma membrane

Question 14

Which coated vesicle returns to ER from Golgi?

Answer 14

COPI

Question 15

Which coated vesicle travels from ER to Golgi?

Answer 15

COPII

Question 16

Describe the structure of clathrin

Answer 16

3 large and 3 small polypeptide chains form a triskelion

Question 17

Triskelions assemble into what?

Answer 17

basket-like structures that form coated pits on cytosolic side of membrane

Question 18

Adaptor proteins form a second layer between what?

Answer 18

cage and membrane

Question 19

Assembly of the clathrin coat protein molecules introduces a ___ in the membrane; and leads to the formation of ___ __

Answer 19

curvature; coated buds

Question 20

In regards to assembly of the clathrin coat, daptor proteins bind what?

Answer 20

clathrin and membrane-bound cargo receptors

Question 21

These play a major role in coat assembly, vesicle formation, and protein trafficking?

Answer 21

Phosphoinositides (PI)

Question 22

True or False?

Interconversions between various PI is highly compartmentalized. It is organelle and domain specific.

Answer 22

true

Question 23

Different proteins bind with high specificity to the ___ of particular PI

Answer 23

headgroups

Question 24

In regards to removal of the clathrin coat, what protein assembles a ring around the clathrin bud?

Answer 24

dynamin

Question 25

Dynamin contains two domains. what are they?

Answer 25

PIP2 binding domain: tethers protein to membrane; GTPase domain: regulates rate of vesicle pinching

Question 26

In regards to removal of the clathrin coat, ___ brings the 2 cytosolic sides of the membrane together and allows them to fuse

Answer 26

pinching

Question 27

Dynamin recruits other proteins that do what to the lipid bilayer?

Answer 27

distort it

Question 28

In regards to removal of clathrin coat, Hsp 70 chaperone protein uses ATP to do what?

Answer 28

peel off coat

Question 29

In regards to vesicle targeting, specificity is achieved by what ?

Answer 29

surface markers on vesicles and complementary receptors on target membrane

Question 30

In regards to vesicle targeting, this protein directs vesicle to specific spots on target membrane

Answer 30

Rab

Question 31

In regards to vesicle targeting, this protein mediates fusion of vesicle with membrane

Answer 31

SNARE

Question 32

The v-SNARE and T-SNARE interaction allows them to wrap around each other and form a bundle. The resulting SNARE complex does what?

Answer 32

locks the vesicle and target membrane together

Question 33

What is the sequence of events in docking and fusion of vesicle?

Answer 33

Rab-GTP tethers with Rab-effector bringing vesicle in closer to target membrane. As docking occurs, V-SNARE and T-SNARE complex forms allowing the vesicle to fuse with the target membrane. Rab-GDP with bound GDI dissociates

Question 34

After the vesicle has fused, what allows the SNARE complex to dissociate?

Answer 34

NSF and accessory protein separation by formation of ADP + Pi

Question 35

In regards to transport from ER, what is quality control?

Answer 35

incompletely folded/misfolded proteins are retained in ER by binding to chaperone proteins such as BiP or calnexin and are then degraded