Protein Synthesis and Secretion

Question 1

What are the main functions of the SER?

Answer 1

1) Synthesis of lipids
2) Calcium Storage and Release
3) Glycogen Metabolism
4) Drug Detox

Question 2

Where does synthesis of lipids occur specifically?

Answer 2

Cystolic side of the SER membrane (must be flipped to luminal side by flippases)

Question 3

Where does phosphorylation of N-linked oligosaccharides occur?

Answer 3

cis Golgi network

Question 4

Where does sulfation of N-linked oligosaccharides occur?

Answer 4

trans-golgi network on tyr residues

Question 5

Where does modification and addition of N-linked oligosaccharides occur?

Answer 5

Golgi cisternae

Question 6

What are the modification of N-linked oligosacchairdes?

Answer 6

1) Removal of Mannose

2) Addition of GlcNAx, Galactose, and Sialic Acid

Question 7

Where are the enzymes that synthesize sphingomyelin and glycolipids from ceramide located?

Answer 7

Lumen of the golgi cisternae

Question 8

Where are phospholipids, cholesterol, and ceramide synthesized?

Answer 8

Cystolic side of SER membranes

Question 9

What are the 3 paths of secretion from the trans Golgi network?

Answer 9

1) Constitutive Secretion
2) Regulated Secretion
3) Lysosome Pathway

Question 10

What is the default pathway (Golgi network secretion)

Answer 10

Constitutive Secretion

Question 11

What is the name of the compartment that connects the RER with the cis Golgi network?

Answer 11

Tubular Vesicular Network aka TVN

Question 12

What does the coated transport vesicle COP1 do?

Answer 12

RETROGRADE transport of vesicles

1) Tubular Vesicular Network to RER
2) Cis Golgi network to RER
3) Trans to Cis between cisternae of Golgi stack

Question 13

What does the coated transport vesicle COPII do?

Answer 13

ANTEROGRADE Transport of Vesicles

1) Transitional RER to Tubular Vesicular network, or cis
2) Tubular vesicular network to cis golgi network

Question 14

Where do clathrin-coated vesicles transport to?

Answer 14

Transport BOTH anterograde and retrograde between the trans-Golgi network and other cell compartments

Question 15

What is Adaptor Protein (AP)?

Answer 15

The clathrin coat contains adaptor protein. It binds to the sorting signal of the protein & couples it to the protein coat of the budding transport vesicle

Question 16

What is the role of ARF and Rab?

Answer 16

They regulate activity of adaptor proteins during coat formation.

Question 17

What membrane GTPase is required to pinch off the budding transport vesicles?

Answer 17

Dynamin

Question 18

Where does translation always begin?

Answer 18

Free ribosomes in the cytosol

Question 19

The ER is continuous with the outer membrane of this structure?

Answer 19

The nuclear envelope

Question 20

Are the lumens of the SER and RER continuous?

Answer 20

Yes

Question 21

What is the main difference between RER and SER?

Answer 21

RER has bound ribosomes active in translation and SER has no ribosomes

Question 22

What is the transport step, protein coat, and cargo protein for the KDEL signal sequence?

Answer 22

Retrograde, COPI, luminal RER

Question 23

What is the transport step, protein coat, and cargo protein for the KKXX signal sequence?

Answer 23

Retrograde, COPI, and RER membrane

Question 24

What is the transport step, protein coat, and cargo protein for the di-acidic (DXE) signal sequence?

Answer 24

Anterograde, COPII, and membrane and secreted;

X stands for any amino acid

Question 25

What is the transport step, protein coat, and cargo protein for the mannose-6-P signal sequence?

Answer 25

Anterograde/Retrograde, Clatharin, and lysosomal