Vesicular transport

Question 1

What does the vesicular pathway look like?

Answer 1

E=exo, G=endo R=retrieval
Endoplasmic reticulum
                    ER
             Golgi apparatus
         ER             E           ER
late endosome      sec. vesicl
     GR        G      E           E
lysosome
                  G      E            E
 early endo.
 GR             R       E            E
         Rec endo.
 GR             R       E            E
Extracellular space

Question 2

How many well known coat proteins are there?

Answer 2

Four.

Question 3

Name the four well characterized coat proteins that Dr adams mentioned.

Answer 3

Clathrin
COP I (coatamer protein 1)
COP II (coatemer protein 2)
Retromer

Question 4

Are there multiple types of clathrin?

Answer 4

yes.

Question 5

trans vs cis Golgi networks.

Answer 5

trans exports towards the plasma membrane.

cis takes imports from the ER

Question 6

Where are the following found.
Clathrin
COP I
COP II
Retromer

Answer 6

Clathrin: PM and trans-Golgi
COP I: cis-Golgi
COP II: ER
Retromer:

Question 7

What are v-SNAREs, and t-SNAREs involved in?

Answer 7

v-SNAREs are on vesicles, they bind to T-SNAREs which exist on surface of the cellular compartments. They make a docking complex.

Question 8

What is the basic structure of clathrin?

Answer 8

It has three heavy chains with smaller light chains binding near the connecting point to the heavy chains. The heavy chains interconnect to form the helical structure.

Question 9

Explain how the below are involved in bud formation.
Cargo Receptors
Cargo molecules
clathrin
adaptins

Answer 9

Cargo molecules bind to their cargo protein (which is in the ER lumen). This allows them to bind an adaptor protein. This protein allows clathrin to bind, which binds to other clathrins holding cargo receptors next to each other while causing a vesicle to form.

Question 10

What happens to clathrin and adaptin shortly after vesicle formation?

Answer 10

They break off the vesicle and are recycled.

Question 11

Where does retromer assemble?

Answer 11

On endosomes.

Question 12

Where does the retromer retrieval pathway return material to?

Answer 12

The golgi apparatus.

Question 13

Why does retromer dimerize?

Answer 13

To make the curvature necessary for a cell.

Question 14

What are the four subunits of retromer.

Answer 14

SNX1
VPS29
VPS35
VPS26

Question 15

What do the subunits below do? 
SNX1
-BAR domain
-PX domain
VPS29
VPS35
VPS26

Answer 15

SNX1: point of dimerization
-BAR domain: attachment point
-PX domain: Binds to phophoinositide in the membrane
VPS29:
VPS35:
VPS26:

Question 16

Are the domains unique to SNX1?

• BAR domain
• PX domain

Answer 16

No, they are found in many other proteins.

Question 17

How many different form of phosphinositides are possible to make?

Answer 17

There are 8 different combination that can be made through phosphorylation and dephosphorylation.

Question 18

Why does it matter the number of phosphinositides exist?

Answer 18

Each binds different proteins.

Question 19

What is dynamin.

What does dynamin do?

Answer 19

it is a monomeric GTPase.

it pinches of the ‘neck’ of a forming vesicle. Then causes it to pinch off, vesicle scission.

Question 20

Mutations of dynamin can cause it to do what?

Answer 20

Mutation can cause failure of scission, or increased scission.

Drosophila mutant shibire, paralyzed because it cannot recycle (endocytose) its vesicles back into the cell.