Protein Trafficking

Question 1

Proteins enter the nucleus via ___ ___. _____ hydrolysis provides directionality.

Answer 1

Nuclear pores
GTP

Question 2

These organelles are interconnected through the process of vesicular transport

Answer 2

ER, Golgi, endosomes, lysosome, and plasma membrane

Question 3

In the mitochondria proteins are ____ and pulled through a translocation channel by ____ ____.

Answer 3

Unfolded
Chaperone ATPase

Question 4

_____ _____ are necessary and sufficient to direct proteins to the proper location

Answer 4

Signal sequences

Question 5

_____ proteins have no signal sequence, default.

Answer 5

Cytosolic

Question 6

Nuclear pore complex acts as a selective gate. It prevents free passage of ____ molecules, 60,000 daltons or larger. An entire ribosome can pass through.

Answer 6

Large

Question 7

____ ____ ____ is the signal that is recognized by nuclear import receptor proteins.

Answer 7

Nuclear localization signal (NLS)

Question 8

Fibrils that extend from the nuclear pore complex form a _____, and that interacts with nuclear import receptors.

Answer 8

Meshwork

Question 9

______ binds to the nuclear import receptor, which allows the proteins to be delivered into the nucleus. The receptor with bound GTP travels back to the cytosol. GTP is ____ into GDP, dissociates from the receptor in the _____.

Answer 9

Ran-GTP
Hydrolyzed
Cytosol

Question 10

Ran GTP is ____ (on/off), binds to receptor displacing cargo. Ran GDP is _____ (on/off), dissociates from the receptor, allowing another cargo to bind.

Answer 10

On
Off

Question 11

GAP is GTPase activating protein which turns G proteins _____ (on/off) by activating the GTPase activity of the G protein, resulting in the hydrolysis of GTP to GDP.

GEF is a guanine nucleotide exchange factor that turns G proteins _____ (on/off) by exchanging GDP for GTP.

Answer 11

Off
On

Question 12

Practice question

Answer 12

C

Question 13

Protein translocators transport ____ proteins across the outer and inner membrane of the mitochondria

Answer 13

Unfolded

Question 14

True or false, mitochondrial chaperones use energy from ATP to pull in and re-fold proteins

Answer 14

True

Question 15

The rough ER is the major entry point for the _____ pathway, which sends proteins to multiple locations

Answer 15

Secretory

Question 16

Proteins pass through a protein translocator into the ER lumen as they are being translated. This is referred to as _____.

Answer 16

co- translational translocation

Question 17

The _____ driving transport comes from protein synthesis itself and from chaperones in the ER lumen

Answer 17

Energy

Question 18

A hydrophobic ____ _____ _____, on transmembrane proteins expels the growing polypeptide from the channel into the ER membrane, and the remainder of the cytosolic portion is synthesized

Answer 18

Stop transfer sequence

Question 19

Vesicular transportation is energetically unfavorable and requires input of energy
True or false

Answer 19

True

Question 20

Vesicle budding is driven by proteins called ____ and ____ , between the ER and Golgi. A third protein called ____ drives endocytosis and post Golgi trafficking.

Answer 20

COPI and COPll
Clathrin

Question 21

Vesicle budding is driven by the assembly of a ____ ____.

Answer 21

Protein coat

Question 22

____ ____ removes the clathrin coat which is recycled. The vesicle is no longer coded and is available to fuse with target membranes.

Answer 22

Uncoating ATPases

Question 23

_____ _____ is a disease that occurs when mutations disrupt the uptake of LDL into cells, resulting in high circulating LDL and cholesterol levels

Answer 23

Familial hypercholesterolemia (FH)

Question 24

Identity of donor, transport, and target membranes is marked by _______ lipids and _____ proteins

Answer 24

Phosphatidylinositol
Rab

Question 25

Different combinations of ____ proteins, provide markers for different transport vesicles and organelles. In their active GTP-bound state, _____ bind to their specific effector proteins, known as _____ proteins, on the target membrane.

Answer 25

Rab
Rab
Tethering

Question 26

_____ proteins Drive vesicle fusion. Winding of ______ with _____ draws the two membranes close enough to cause their fusion.

Answer 26

SNARE
vSNAREs
tSNAREs

Question 27

Constitutive secretory pathway (default) does not require a signal sequence and proteins are secreted outside of the cell
True or false

Answer 27

True

Question 28

Diversion to the ____ and ____ _____ when leaving the Golgi, requires a specific signal

Answer 28

Lysosome
Secretory granules

Question 29

Addition of a ____ ____ ___ in the Golgi targets proteins to lysosomes.

Answer 29

Phosphorylated mannose tag (M6P)

Question 30

Practice question

Answer 30

E

Question 31

Practice question

Answer 31

B

Question 32

Practice question

Answer 32

C