Lecture #9

Question 1

In multispanning proteins, sequential transmembrane segments typically have _______ orientations, so their arrangement in the membrane is determined by the direction in which the ______ segment is inserted

Answer 1

opposite, first

Question 2

_____-________ proteins lack a signal sequence, but are synthesized in the cytoplasm, and targeted to the ER through interactions with proteins in the Get (Guided Entry of Tail-Anchored proteins) pathway

Answer 2

Tail-anchored

Question 3

Membranes are ________ with a cytosolic face and a luminal/extracellular face established in the ER

Answer 3

asymmetric

Question 4

Nearly all proteins produced on RER become _________

Answer 4

glycoproteins

Question 5

Addition of sugars to an oligosaccharide is catalyzed by _____________, each transfers a specific monosaccharide to the growing end of the carbohydrate chain

Answer 5

glycosyltransferases

Question 6

The sugar arrangement in the oligosaccharide chains of a glycoprotein depends on the _______ ________ of enzymes in the assembly line

Answer 6

spatial localization

Question 7

Segment of each carbohydrate chain is not assembled on the protein itself but put together independently on a _____ ______, which is called dolichol phosphate, embedded in the ____ _______.

Answer 7

lipid carrier, ER membrane

Question 8

Sugars are added to the dolichol phosphate molecule one at a time by membrane-bound ___________

Answer 8

glycosyltransferases

Question 9

Misfolded proteins will be glucose tagged, mannose deficient and ultimately degraded by __________ (ER-associated degradation)

Answer 9

proteasomes

Question 10

Accumulation of misfolded proteins triggers the ?

Answer 10

unfolded protein response (UPR)

Question 11

During the UPR, sensors in the ER are kept ________ by the chaperone BiP. When misfolded proteins accumulate, BiP is incapable of _________ the sensors.
Activated sensors send signals to trigger proteins involved in _________ of misfolded proteins.

Answer 11

inactive, inhibiting, destruction

Question 12

The ER to the Golgi Complex is the ______ step in vesicular transport

Answer 12

first

Question 13

RER have specialized _____ sites where transport vesicles are formed (no ribosomes)

Answer 13

exit

Question 14

Transport vesicles fuse with one another and form the ERGIC (endoplasmic reticulum Golgi intermediate compartment) toward the _____ ______

Answer 14

Golgi complex

Question 15

The Golgi complex has several functionally distinct compartments:
____ face of the Golgi faces the ER
____ face is on the opposite side of the stack.

Answer 15

cis, trans

Question 16

The ____ Golgi network functions to sort proteins for the ER or the next Golgi station.

The ____ Golgi network functions in sorting proteins to the plasma membrane or various intracellular destinations.

Answer 16

cis, trans

Question 17

The Golgi complex is/ is not uniform in composition

Answer 17

is not

Question 18

Assembly of carbohydrates found in glycolipids and glycoproteins takes place in the _____

Answer 18

Golgi

Question 19

Sequence of incorporation of sugars into oligosaccharides is determined by ____________

Answer 19

glycosyltransferases

Question 20

In the _______ transport model, cargo is shuttled from the CGN to the TGN in vesicles

Answer 20

vesicular

Question 21

In the _________ maturation model, each cistern “matures” as it moves from the cis face to the trans face

Answer 21

cisternal

Question 22

Current model: similar to cisternal maturation model but with vesicle retrograde transport. Golgi cisternae serve as a primary _________ carriers.

Answer 22

anterograde

Question 23

Materials are carried between compartment using _______ vesicles

Answer 23

coated

Question 24

Protein coats have two functions: ?

Answer 24

Cause the membrane to curve and form a vesicle.
Select the components to be carried by vesicle.

Question 25

? : move materials from the ER “forward” to the ERGIC intermediate compartment and Golgi complex

Answer 25

COPII-coated vesicles

Question 26

? : move materials from ERGIC and Golgi “backward” to ER, or from the trans Golgi to the cis Golgi cisternae

Answer 26

COPI-coated vesicles

Question 27

? : move materials from the TGN to endosomes, lysosomes, and plant vacuoles

Answer 27

Clathrin-coated vesicles

Question 28

COPII coated vesicles bud off specialized domains of the ER called ?. This begins the biosynthetic pathway.

Answer 28

ER exit sites (ERESs)

Question 29

ER export signals found in ______ tails of transported proteins

Answer 29

cytosolic

Question 30

COPII coats select and concentrate enzymes such as glycosyl-transferases, vesicle docking proteins and ____ selecting proteins

Answer 30

cargo

Question 31

All vesicles have two distinct layers: ?

Answer 31

an outer scaffold
an inner layer of adaptor (or adaptor-like) proteins

Question 32

The structure of the outer scaffolds are very different;

1. the subunits of the clathrin lattice (three-legged clathrin complexes) _______ extensively
2. the COPII lattice does/ does not overlap. Each vertex of a COPII coat is formed by four edges rather than three (clathrin and perhaps the COPI coat).

Answer 32

overlap, does not

Question 33

COPI coat is made up of a complex called a _________ that is made up of seven proteins

Answer 33

coatamer

Question 34

COPI-coated vesicles have been most clearly implicated in the retrograde transport of proteins, including the movement of: ?

Answer 34

Golgi resident enzymes in a trans-to-cis direction
ER resident enzymes from the ERGIC and the Golgi complex back to the ER.

Question 35

Organelle proteins are maintained by: ?

Answer 35

Retention of resident molecules excluded from transport vesicles.
Retrieval of “escaped” molecules back to their normal compartment.

Question 36

Resident proteins of the ER contain an amino acid sequence at the C-terminus serving as a _____ _______

Answer 36

retrieval signal

Question 37

What are the 4 important compounds in COPI-coated vesicles?

Answer 37

K - Lysine
D - Aspartic Acid
E - Glutamic Acid
L - Leucine