2.2

Question 1

progeny genomes and proteins must be ___________ at the intracellular site of virion assembly

Answer 1

concentrated

Question 2

where do envelopes come from

Answer 2

host membranes

Question 3

membrane protein location, modification, and folding are all mediated where

Answer 3

ER and Golgi

Question 4

what must be localized to assembly sites on the envelope

Answer 4

matrix or tegument proteins

Question 5

where are matrix and tegument proteins located

Answer 5

between nucleocapsid and the envelope

Question 6

what does long distance movement require (2)

Answer 6

energy
motor proteins on cytoskeleton tracts

Question 7

what does short distance movement need

Answer 7

energy dependent pores

Question 8

what viruses need to get to the nucleus

Answer 8

DNA viruses

Question 9

how is the viral genome imported into the nucleus

Answer 9

nuclear localization signals

Question 10

what are nuclear localization signals

Answer 10

small amino acids recognized by host importin proteins

Question 11

what does importin do

Answer 11

they carry the viral genome or proteins through the nuclear pore into the nucleus

Question 12

what do importins recognize

Answer 12

nuclear localization signals

Question 13

what drives the movement through the nuclear pore complex

Answer 13

RAN-GDP gradient

Question 14

where is RAN-GDP high

Answer 14

cytoplasm

Question 15

where is RAN-GTP high

Answer 15

nucleus

Question 16

do viruses express NLS’s

Answer 16

yes to be recognized by importins

Question 17

what complex binds a nuclear pore

Answer 17

importin a and b
cargo with NLS

Question 18

why does importin b let go of the cargo in the nucleus

Answer 18

because it binds better to RAN-GTP and gets exported out into the cytoplasm with it

Question 19

where are viral membrane proteins made

Answer 19

the rough ER

Question 20

translation into the ER is induced by what

Answer 20

a hydrophobic signal sequence encoded on the viral mRNA that protrudes from a free ribosome

Question 21

where does protein folding and disulphide bonding happen

Answer 21

ER

Question 22

where does the hydrophobic signal sequence on viral mRNA come from

Answer 22

its encoded in the viral mRNA

Question 23

signal sequence recognition

Answer 23

1. free ribosome starts translating mRNA
2. signal sequence emerges from ribosome and gets recognized by signal recognition particle In the cytosol
3. signal particle receptor binds to SRP receptor on the ER membrane
4. signal sequence is translocated into the ER lumen

Question 24

maturation of stuff as it travels through ER and Golgi (6)

Answer 24

1. translocation and signal sequence cleavage
2. disulphide bond formation
3. folding and adding oligosaccharides
4. oligomerization
5. oligosaccaride trimming and modified additions
6. protein cleavage

Question 25

whats the core oligosaccharide

Answer 25

N-acetylglucosamine mannose glucose

Question 26

what goes trimmed during oligosaccharide trimming

Answer 26

3 glucose 1 mannose

Question 27

where ensures that only the properly folded proteins leave and continue

Answer 27

ER

Question 28

steps of ER quality control system

Answer 28

1. protein glycosylation 2. trimming 3. binding of calnexin and ERP57 4. folding and disulfide bond addition by calnexin and ERP57

Question 29

glycosylation in ER structure

Answer 29

3 glucose (Glc) 9 mannose (Man) 2 N-acetylglucosamine (GlcNAc)

Question 30

what allows calnexin and ERP57 to bind

Answer 30

the single glucose left from trimming

Question 31

what enzyme recognizes if the protein is misfiled in the ER

Answer 31

UGGT

Question 32

2 potential outcomes for misfolded proteins

Answer 32

can either have the glucose added again to try again or be degraded if it doesn't work

Question 33

calnexin–calreticulin cycle

Answer 33

ensures that only correctly folded glycoproteins exit the ER.

Question 34

what channel sends misfolded proteins to be degraded

Answer 34

retro-translocation channel

Question 35

whats a variation in the secretory pathway

Answer 35

proteins can also gave ER and Golgi retention signals that maintain their location in these compartments

Question 36

secretory pathway

Answer 36

route proteins take from the ribosome → ER → Golgi → final destination. This pathway ensures proper folding, modification, and sorting of proteins before they reach where they need to function

Question 37

where is the matrix in HIV

Answer 37

gag polyprotein

Question 38

what does the matrix region (M) bind

Answer 38

both the viral membrane proteins and the nucleocapsid proteins

Question 39

where does the M protein sit

Answer 39

it lines the inner surface of the viral envelope

Question 40

what does M1 bind to

Answer 40

nucleocapsid of nuclear genomes

Question 41

what does NS2 or NEP bind to

Answer 41

M1 on the genomes

Question 42

NEP/NS2

Answer 42

nuclear export proteins

Question 43

what do NS2 or NEp do

Answer 43

shuttle ribonucleoprotein (complex of viral RNA and proteins essential for replication) from nucleus into cytoplasm

Question 44

how do RNPs move to the plasma membrane

Answer 44

microtubules

Question 45

N and M associated RNA does what

Answer 45

gets shuttled to the plasma membrane

Question 46

binding of M-coated RNA to VSV-G does what

Answer 46

drives budding and virion formation

Question 47

RNP binding proteins (2)

Answer 47

Matrix nucleoproteins

Question 48

what does N (nucleoprotein) do

Answer 48

binds RNA to form a RDP complex