Intracellular Trafficking

Question 1

Virion components are produced in multiple cellular “compartments” T/F

Answer 1

T

Question 2

Animal cell diameters range between

Answer 2

10-30 micrometers

Question 3

_____ is not sufficient for intracellular trafficking

Answer 3

diffusion

Question 4

Viral components are most commonly moved on

Answer 4

microtubules

Question 5

Assembly of most ___ virus takes place in the nucleus

Answer 5

DNA ex. adenovirus, papillomavirus

Question 6

Structural proteins are ____ into the nucleus after syn.

Answer 6

imported

Question 7

Assembly of herpesvirus is within the ____; however it is finished at _______ sites.

Answer 7

nucleus; extra-nuclear

Question 8

All viral structural proteins enter the nucleus via the ___________

Answer 8

normal cellular pathway of nuclear protein import

Question 9

Proteins destined for the nucleus encode ______

Answer 9

nuclear localization signals

Question 10

The nuclear localization signals are recognized by the

Answer 10

nuclear import machinery

Question 11

Entry into the nucleus can be done when the protein is ____; such as polyomavirus, or via a ____ _____, such as an adenoviral protein

Answer 11

preassembled; viral chaperone

Question 12

The nucleus has 3k to 4k ____ _____ _____, each with a very high translocation capacity

Answer 12

nuclear pore complex

Question 13

_____ ______ depends on the limited supply of soluble transport proteins.

Answer 13

Nuclear import

Question 14

viral and cellular proteins ____ for entry into the nucleus

Answer 14

compete

Question 15

large DNA viruses produce so many structural proteins that cellular protein synthesis is _____

Answer 15

inhibited

Question 16

Many viral structural proteins enter infected nuclei as _____ structural components

Answer 16

multimeric

Question 17

viral membrane proteins reach their destination via the cellular ____ ______

Answer 17

secretory pathway

Question 18

Viral envelope glycoproteins are translated into the ___ _____ and folded and assembled there

Answer 18

ER lumen

Question 19

They travel via ______ _______ to and through the golgi apparatus and from golgi to plasma membrane

Answer 19

transport vesicles

Question 20

The _____ ______ of the virus and the viral genome are also directed to plasma membrane sites of assembly

Answer 20

internal proteins

Question 21

Transmembrane segments of glycoproteins usually separate _____ extracellular from _____cytoplasmic domains

Answer 21

large; smaller

Question 22

________ domains are crucial for viral entry, whereas the ______ are important in virus assembly

Answer 22

extracellular; intracellular

Question 23

Ribosomes synthesizing proteins for the secretory pathway are generally found on the ____ face of the ___

Answer 23

Cytoplasmic; ER

Question 24

The association of ribosomes with the ER membrane is directed by a short sequence in the ____ protein called the ____ _____>

Answer 24

nascent; signal peptide

Question 25

Signal peptides are found at the __-termini of proteins destined for the secretory pathway

Answer 25

N

Question 26

Signal peptides are approximately ____ amino acids in length

Answer 26

20

Question 27

The signal peptide is recognized by the ____ _____ _____

Answer 27

signal recognition particle

Question 28

What are the steps of influenza virus HA0 protein maturation?

Answer 28

1. Translocation 2. disulfide bond formation/glycosylation 3. protein folding

Question 29

Translocation continues until what enters the ER lumen?

Answer 29

The entire polypeptide chain

Question 30

The folding and initial _______ ______ of proteins that enter the secretory pathway take place in the ER

Answer 30

postranslational modification

Question 31

The lumen contains many ____; which help to catalyze chemical modifications such as disulfide bond formation, glycosylation, folding promotion, oligomerization

Answer 31

enzymes

Question 32

Viral envelope glycoproteins are modified by the addition of oligosaccharides to _____, ______, or _____

Answer 32

asparagine, serine, or threonine

Question 33

each glycoprotein population comprises a heterogenous mix of _____

Answer 33

glycoforms

Question 34

The hydrophilic oligosaccharides are present on the surface of a virus, creating a ____ ____, which in effect masks the protein's surfaces and epitopes which can be recognized by _____ antibodies

Answer 34

sugar shell; antiviral

Question 35

Intramolecular disulfide bonds occur between pairs of ____ residues

Answer 35

cysteine

Question 36

disulfide bonds would rarely form in the ____ environment of the cytoplasm; but the ____ environment of the ER lumen is a good location for this

Answer 36

reducing; oxidizing

Question 37

most viral membrane proteins are _____ that assemble as their constituent protein chains are folded and covalently modified.

Answer 37

oligomers

Question 38

This assembly begins in the ____ as the surfaces that mediate interactions among protein subunits adopt the correct conformation.

Answer 38

ER

Question 39

HA0 _____are constricted to the ER lumen, whereas _____ are found in this and subsequent compartments of the secretory pathway.

Answer 39

monomers, trimers

Question 40

Herpes simplex type 1 proteins gH and gL must ____ with each other in order to leave the ER

Answer 40

interact

Question 41

The first step of the secretory pathway is transport of the folded protein from the ____ to the ____

Answer 41

ER; Golgi

Question 42

Proteins enter the Golgi Apparatus from the ER via the ___-_____ network.

Answer 42

cis-golgi

Question 43

The ___-____ network forms the exit face of the Golgi.

Answer 43

trans-golgi

Question 44

Some viral envelope glycoproteins are also processed by cellular enzymes in late Golgi compartments. T/F

Answer 44

T

Question 45

Retroviral envelope proteins are cleaved in the trans-golgi to form the TM (transmembrane) and SU (surface unit) subunits from the precursor t/f. What is also cleaved here? What is this essential for?

Answer 45

T; HA0 into HA1 and HA2; formation of an infectious particle. not necessary for assembly

Question 46

in Neurons, transport to (anterograde) synaptic vesicles is controlled by ____ motors. transport to the nucleus (retrograde) is controlled by ____ motors. This is performed along what cellular structure?

Answer 46

kinesin; dynein; microtubules

Question 47

Several virus encode proteins that _____ transport of MHC I molecules to the plasma membrane

Answer 47

interfere with

Question 48

Adenovirus ___ protein binds to MHC in the ___ and prevents exit

Answer 48

E3; ER

Question 49

Human cytomegalovirus US11 and US2 gene products induce transport of MHC from the ER to the ____ for rapid degradation by what cellular enzyme? HIV1 ___ protein induces selective degradation of new MHCI by a similar mechanism

Answer 49

cytosol; proteasome; Vpu

Question 50

Viral envelopes can be acquired from a variety of ____ membranes, not just the plasma membrane. Most assemble at the ____ face of compartments of the _____ pathway

Answer 50

internal membranes; cytoplasmic; secretory

Question 51

Complex virus such as herpesvirus and poxvirus interact with ___ ____ ____ during assembly and exocytosis

Answer 51

multiple internal membranes

Question 52

Viral assembly site is determined by the ____ location of _____ _____ ____

Answer 52

intracellular; viral envelope proteins

Question 53

The synthesis and packing of most ___ genomes takes place in the infected ____ ____

Answer 53

DNA; cell nucleus

Question 54

For most RNA virus, packing and assembly takes place in the _____. These genomes must be relocated to the appropriate ______

Answer 54

cytoplasm; cytoplasmic membrane

Question 55

Retroviral RNA genomes are -___ RNA transcripts synthesized in cell nuclei by host cell ____ ____ __. These genomes must be exported where for assembly? Because of cellular regulations preventing unspliced RNA export from the nucleus; ____ _____ _____ must be encoded to promote their export. What is an example?

Answer 55

unspliced; RNA Pol II; the cytoplasm; viral RNA-binding proteins; HIV Rev1

Question 56

Genomic segments are bound to NP as they are syn. and then by the M1 protein. What does this support? M1 containing RNP are directed to the exportin-1 pathway after binding a NEP that contains a ____ ____ ____

Answer 56

Ribonucleoprotein export; nuclear export signal

Question 57

The NEP contains a C-terminal ___ _____ ____

Answer 57

M1 Binding domain

Question 58

The M1 interacts with the membrane, cytoplasmic domains of HA and NA glycoproteins to initiate assembly and release of enveloped particles.

Answer 58

T

Question 59

Retroviral proteins that mediate membrane association of genomic RNA are similar to _____ ______ of (-) strand RNA virus. Retroviral RNA is translated on ribosomes into ___. What does Gag transport?

Answer 59

matrix proteins; Gag; unspliced viral mRNA