Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

MBOD Week 6 > Vesicle Transport and Secretory Pathways > Flashcards

Vesicle Transport and Secretory Pathways Flashcards

1
Q

Where are proteins that are destined for the secretory pathways translated?

A

By ribosomes on the ER membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What directs proteins that are destined for secretory pathways to the ER?

A

a signal sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Where does N-linked glycosylation of membrane proteins occur?

A

ER lumen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Explain how N-linked glycoslyation occurs in the ER lumen

A
  1. Protein must of the sequence Asn-X-Ser/Thr
  2. A branched oligosaccharide linked to a membrane lipid looks for asparginine sequence
  3. the branched oligosaccharide is transferred to the asparginine amide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the purpose of N-linked surgar modifications?

A
  1. Direct sorting to different parts of the cell

2. can be involved in Cell-cell recognition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When does disulfide bond formation typically occur?

A

During or soon after synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What protein catalyzes breakage and reformation of disulfide bonds?

A

protein disulfide isomerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the purpose of the making and breaking of disulfide bonds done by protein disulfide isomerase?

A

it allows the protein to get into the most thermodynamically stable conformation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What type of proteins typically have disulfide bonds?

A

secretory and membrane proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What effect does the cytosol have on disulfide bond formation?

A
  • Prevents formation

- This is because the cytosol is a reducing environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

T or F: both properly and improperly folded proteins are transported out the ER

A

True

Properly folded proteins are transported out via formation of a vesicle

Improperly folded proteins are transported out via translocation channel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What proteins that exist within the ER aid in protein folding?

A

Chaperones assist unfolded proteins in achieving the most thermodynamically stable conformation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

T or F: oligomeric proteins such as antibodies may be transferred out of the ER and assembled in the cytoplasm

A

False - the protein must be fully assembled before being transported out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens to mis-folded proteins in the ER?

A
  1. they are transported out via reverse transport through translocation channel
  2. Deglycosylated and Ubiquitylated in the cytosol
  3. Degraded by a proteasome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What causes stimulation of chaperone synthesis?

A
  • this is called the unfolded protein response

- occurs when unfolded proteins accumulated in the ER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What diseases result from alpha anti-trypsin deficiency?

A
  • Emphysema (major genetic cause)
  • Liver disease
  • hepatocellular carcinoma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the job of alpha anti-trypsin ?

A

inhibition of elastase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What types of cells typically secrete alpha anti-trypsin (3 types) ?

A
  1. hepatocytes
  2. macrophages
  3. neutrophils
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the most common cause of alpha anti-trypsin deficiency?

A
  • single AA change causes mis-folded protein

- protein is expelled from ER and degraded by proteasome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is caused by mutation F508del and why does this deletion cause disease?

A
  • cystic fibrosis
  • oligosaccharide side chains are not processed properly
  • protein then misfolds and is degraded
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How are proteins transferred from the ER to the golgi, lysosomes, or plasma membrane?

A

Transport vesicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the job of protein coats in vesicular transport?

A
  • Allows for selection of appropriate cargo proteins for transportation
  • Form basket-like complexes that deform membrane before it pinches off into a vesicle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are 3 types of protein coats?

A

Clathrin
COPI
COPII

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

In what types of vesicles is clathrin found?

A
  1. exocytic formed at TRANS golgi network

2. Endocytic vesicles formed on the plasma membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

In what types of vesicles is COPI found?

A
  1. vesicles moving through Golgi in an anterograde fashion

2. vesicles formed on Golgi that are bound for ER membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

In what types of vesicles is COPII found?

A

Vesicles formed in ER that are bound for CIS-golgi

27
Q

What are the steps in clathrin-coated vesicle formation?

Note: this serves as a general model for coat formation

A
  1. clathrin triskelions form a basket-like structure
  2. clathring lattice induces vesicle budding
  3. Adaptin (contained on Clathrin coated vesicles) binds transmembrane prots. and cargo receptors
  4. Dynamin (GTPase) works with other prots. to pinch of vesicle
  5. vesicles loose prot. coat soon after pinching off
28
Q

What proteins mediate targeting of the vesicles?

A

Rabs
Tethers
SNAREs

29
Q

What proteins mediate initial vesicle recognition?

A

Rabs and Thethers bind to each other

30
Q

What do SNAREs do and how do they work?

A
  • they ensure additional specificity
    1. vSNARE (on vesicle) binds tSNARE (on target membrane)
    2. The two interwrap pulling the membranes together promoting fusion
31
Q

T or F: the morphology of coats formed by COP proteins differs from the clathrin coat

32
Q

What protein coats allows for ER cargo receptors and other ER resident proteins to be returned to the ER?

33
Q

What allows for selectivity in COPII vesicle packaging?

A

Association of the ER proteins with cargo receptors

34
Q

Why does retrograde transport from golgi to ER occur and what protein mediates this movement?

A
  • Occurs because ER needs to retrieve ER cargo receptors ans soluble ER resident proteins that were mis-sorted to the cis-Golgi
  • COPI mediates movement
35
Q

How does retrieval of transmembrane ER proteins occur?

A

Di-lysine sequence binds directly to the COPI coat

36
Q

How does retreival of lumenal ER proteins occur?

A
  • mediated by ER retention signal (c-terminus KDEL) on the lumenal ER prot. binding to the KDEL receptor in cis-golgi membrane
37
Q

What happens to surgar modifications as proteins that have exited the ER move to the GolgI?

A

They pass through cisternae to the trans face and acquire increasingly complex sugar modifications

38
Q

Why does the golgi reside in the vicinity of the centrosome?

A

because its localization is dependent on microtubules

39
Q

What are the 3 regions make up the golgi, and what is the job of the golgi?

A

cis
medial
trans

40
Q

What is the golgi function?

A

sorting and glycosylation

41
Q

What are two real-time techniques that allow for visualization of sorting proteins?

A
  1. GFP labeled proteins
  2. Temperature sensitive mutants that have wild type activity at normal temperatures and defective at the restrictive temp
42
Q

Where do proteins exit the golgi, and what are the possible destinations for these proteins?

A
  1. Plasma membrane
  2. secretory vesicles
  3. lysosomes
43
Q

Describe the default pathway for proteins targeted for the plasma membrane.

A
  • no specific targeting sequence

- exocytosis occurs independent of any known stimulus

44
Q

Describe regulated secretion/exocytosis

A
  1. vesicle contents are stored in special secretory vesicles

- these vesicles are released in response to nuerotransmiter or hormonal cell stimulation

45
Q

Describe the maturation process of secretory vesicles

A
  • Mature vesicles have more densely packed protein

- Often maturation includes proteolytic processing

46
Q

What is famili hyperinsulinemia-an?

A

asymptomatic condition in which pro-insulin isn’t cleaved

this leads to a build of pro-insulin

47
Q

What coat proteins will be used on a vesicle traveling from the golgi to the lysosome via endosomes have?

A

clathrin + GGA adaptor

48
Q

What coat proteins will be used on a vesicle traveling from golgi to plasma membrane?

A

clathrin + adaptin 1

49
Q

What coat proteins will be used on a vesicle traveling from plasma membrane to endosomes?

A

clathrin + adaptin 2

50
Q

What coat proteins will be used on a vesicle traveling from ER to Golgi?

51
Q

What coat proteins will be used on a vesicle traveling from Golgi cisterna to golgi cisterna?

52
Q

What coat proteins will be used on a vesicle traveling from golgi to ER?

53
Q

What would occur if decoating of clathrin and COP coats did not occur after the vesicle was moved into the cytosol?

A

The proper recognition proteins would not be exposed and proteins would not go to the correct compartment

54
Q

What rab, vSNARE, and tSNAREs are involved in Ach release?

A 
vSNARE = VAMP
Rab = Rab3A
tSNARE = syntaxin
55
Q

What is the retrieval signal for lumenal proteins that have been mistakenly transferred to the ER and how does this pathway work?

A

KDEL receptor binds to the KDEL sequence on the lumenal protein

KDEL receptor then binds the COPI coat

Binding the COPI coat induces budding so the vesicle can travel back to the ER

56
Q

What is the retrieval signal for transmembrane proteins that have been mistakenly transferred to the ER and how does this pathway work?

A

Transmembrane proteins contain a cytosolic di-lysine retreval signal

COPI binds and returns vesicle

57
Q

What is the default pathway for proteins that lack a specific signal on the vesicle?

A

Constitutive secretion

This uses Clathrin + AP1 to send localize the vesicle to the plasma membrane and send the protein out of the cell

58
Q

What does regulated secretion depend on in order to occur?

A

signals such as hormones or neurotransmitter

Uses Clathrin + AP1

59
Q

What protein carries vesicles to the synapse in an axon and what is this protein dependent on?

A

Kinesin = ATP depedent

60
Q

What type of cytoskeletal structure is dependent on ARP and Rac?

A

Lamellipodial actin

61
Q

What do Taxol and Pacitaxel do?

A

Stabilize microtubules, preventing disassembly

62
Q

What neurotransmitter’s release is dependent on Syntaxin and VAMP?

A

Ach (syntaxin = tSNARE, VAMP = vSNARE)

63
Q

What arrests translation of nascent proteins by recognizing a hyrdophobic signal sequence?

A

SPR - signal recognition particle

64
Q

Explain how chaperon transcription can be upregulated by unfolded protein

A
  1. Protein binds receptors with a cytoplamic kinase
  2. Kinase phosphorylates transcription factor(s)
  3. Factor goes into the nucleus and activates the chaperon gene

MBOD Week 6 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions