Lecture 6

Question 1

What is the purpose of COP II vesicles?

Answer 1

ER to golgi transport (anterograde)

Question 2

What is the purpose of COP I vesicles?

Answer 2

Goli to ER transport (retrograde)

Question 3

What is the purpose of clatherin coated vesicles?

Answer 3

Transport from the cell membrane to the trans golgi or to the late endosome

Question 4

What are the two types of proteins that make up a snare complex?

Answer 4

vSnares and tSnares

Question 5

What are the basic steps in vesicle transport?

Answer 5

Recruitment of coating protein driving the budding process
Pinching off of bud
loss of coating proteins
Snare Complex interactions
Transport driven via microtubules

Question 6

What causes the COP II coat to be recruited in the ER?

Answer 6

Sec 12 in the vesicle membrane binds sar1, this results in GTP hydrolysis by Sar1 allowing it to act as an anchor recruiting the sec 23/24 proteins which forms the COP II coat

Question 7

What causes loss of the COP II coat?

Answer 7

Sar12 rebinds GTP resulting in a conformational change which releases its ‘anchor’ to the cell membrane

Question 8

What is the purpose of retrograde transport?

Answer 8

To return mis-sorted proteins required for ER function to the ER from the golgi

Question 9

What sequence does retrograde transport use to make sure that the correct proteins are returned to the ER?

Answer 9

The KDEL sequence

Question 10

What is the KDEL sequence?

Answer 10

Lys-Asp-Glu-Leu

Question 11

What causes proteins to bind to the KDEL receptor in the golgi but not in the ER?

Answer 11

The higher pH of the ER

Question 12

What is the most likely method of proteins being taken into COP II vesicles for anterograde transport?

Answer 12

Bulk Flow

Question 13

What recruits the COP I coat for retrograde transport?

Answer 13

The KDEL sequence when it binds to and ER protein

Question 14

What is the sorting signal on proteins for the formation of COP I transport?

Answer 14

Lys-Lys-X-X

Question 15

What is the sorting signal on proteins for COP II transport for the distal secretory pathway?

Answer 15

Asp-X-Glu

Question 16

How do golgi bodis move from cis golgi to maedial and then trans golgi?

Answer 16

Through cisternal maturation, NOT vesicle transport

Question 17

What GTPase leads to formation of the COP I coat?

Answer 17

Arf

Question 18

What process creates the signal that targets proteins into the lysosome?

Answer 18

Glycosylation

Question 19

What amino acid are the sugars in glycosylation addded to?

Answer 19

Asparagine

Question 20

What sequence signals the ER to add sugars to a protein?

Answer 20

Asn-X-Ser/Thr

Question 21

What is the enzyme that adds the sugars to the protein in asparagine?

Answer 21

oligosaccharyl transferase

Question 22

What is the initial sugar added to proteins that undergo glycosylation?

Answer 22

(Glc)3(Man)9(GlcNAc)2

Question 23

What occurs to the sugar added to proteins?

Answer 23

It is trimmed to (Man)8 core which signals transfer to the golgi

Question 24

How is the sugar modified in the cis golgi to be targeted to the lysosome?

Answer 24

It is changed to a mannose-6-Phosphate

Question 25

What is the difference between clatherin coated vesicles targeted from the trans golgi to the endosome and vesicles from the cell membrane

Answer 25

The vesicles from the cell membrane use AP2 adapter protein and vesicles from the golgi use AP1 adapter protein

Question 26

What causes the pinching off of vesicles from the cell membrane?

Answer 26

Dynamin GTPase makes a collar around the bud resulting in bud formation preserving the integrity of cell membrane

Question 27

What is the sorting sequence for cargo to be recruited via endocytosis?

Answer 27

Asp-Pro-X-Tyr

Question 28

What is an example of endocytosis?

Answer 28

Uptake of LDL by the LDL receptor