Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Med 103 > intracellular protein trafficking > Flashcards

intracellular protein trafficking Flashcards

1
Q

what is protein targeting/sorting

A

mechanism by which proteins are transported to their appropriate destinations in the cell or outside it

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

when does the first step of protein sorting take place

A

while translation is still taking place

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

where are proteins destined for the ER, Golgi apparatus, lysosomes, plasma membrane synthesized on

A

ribosomes that are bound to the ER membrane

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

where are proteins destined for the nucleus, mitochondria, chloroplast and peroxisome synthesized on

A

free (non-bound) ribosomes

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

when can proteins be translated to the ER (2)

A
  1. during their synthesis on membrane-bound ribosomes (co-translational translocation)
  2. After their translation have been completed on free ribosomes in the cytosol (post-translational translocation)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the first step of the Co-translational pathway

A

association of ribosomes with ER

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

what is the specific aa (amino acid) sequence that target ribosomes for binding to the ER membrane

A

signal sequence at the amino (N) terminus of polypeptide

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

what removes the signal sequences

A

proteolytic cleavage.

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

what binds to the ribosome and signal sequence, prevents further translation and targets the complex to the ER

A

signal recognition particle (SRP)

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

what does signal recognition particle (SRP) contain

A

six polypeptides and a small cytoplasmic RNA (srpRNA)

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

after translation inhibition, what does the complex bind to 1

A

SRP receptor on the ER membrane

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

after the SRP is released what does the ribosome bind to

A

translocon

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

what is the translocon a complex of

A

three transmembrane proteins called Sec61

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

what does cleavage of the signal sequence by signal peptidase release

A

polypeptide into the lumen of the ER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what maintains the unfolded conformation of the proteins

A

cytosolic chaperones

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

during post-translational import, what recognizes the signal sequences

A

Sec62/63 complex

17
Q

what does Sec63 protein associate with

A

chaperone protein (BiP)

18
Q

what is the function of chaperone protein (BiP)

A

acts as a molecular ratchet to drive protein translocation into the ER

19
Q

what happens to proteins destined for secretion from the cell or residence within the lumen of ER, Golgi, or lysosome

A

(i) released into the lumen of ER

(ii) translocated across the ER membrane

20
Q

what are the two ways in which insertion occurs

A

(1) with a cleavable signal sequence and a single stop-transfer sequence
(2) with an internal non-cleavable signal sequence

21
Q

what are the N and C terminus of membrane proteins

A

amino (N) or carboxy (C) terminus

22
Q

in the first type of insertion, what happens when the polypeptide chain crosses the membrane

A

signal sequence is cleaved and amino terminus of the polypeptide chain is exposed in the ER lumen

23
Q

what halts translocation in the ER membrane, for the first type of insertion

A

stop transfer sequence

24
Q

in the second type of insertion what does the signal sequence act as

A

anchors the protein in the membrane with its C terminus or N terminus in the ER lumen

25
Q

what determines whether C-terminus or the N-terminus is in the cytosol

A

orientation of the polypeptide chain

26
Q

how does Insertion of a protein that spans the membrane multiple times occur

A

after the signal sequence by repeatedly stopping the sequence

27
Q

ER is the site of

A 
protein folding
assembly of multisubunit proteins,
disulfide bond formation,
the initial stages of glycosylation,
the addition of glycolipid anchors to some plasma membrane
proteins
28
Q

what assists in the 3D folding of polypeptides in the ER

A

Hsp70 chaperone (BiP)

29
Q

what is the function of

a) cytosolic chaperones
b) Mitochondrial chaperones

A

a) stabilize the un-folded configuration

b) facilitate transport and subsequent folding of the polypeptide chain within the organelle

30
Q

what happens to proteins that travel along the secretory

pathway in transport vesicles

A

they bud from the membrane of one organelle and then fuse with the membrane of another

31
Q

what are transmembrane proteins that enter the transitional ER marked with

A

sequences that signal either their export from or retention within the ER

32
Q

what are the export signal sequences

A
  • di-acidic (eg., Asp-Asp or Glu-Glu)

* Di-hydrophobic (eg., Met-Met)

33
Q

what are proteins destined to remain in the ER lumen marked by

A

sequence Lys-Asp-Glu-Leu (KDEL). they exported from ER to Golgi, and are recognized by a receptor in the ERGIC and are transported back to the ER

34
Q

where does protein modification occur in the Golgi

A

at its medial and trans Golgi stacks

35
Q

what are proteins transported through after being processed in the Golgi

A

through the secretory pathway which involves aorting of proteins into different kinds of transport vesicles which bud from the trans Golgi network and deliver their contents to appropriate locations

36
Q

what are the types of coated vesicles

A

COP-coated vesicles (COP1 and COP II)

Clathrin-coated vesicles

37
Q

what vesicles carry secretory proteins from the ERGI or Golgi, budding from the transitional ER and carrying their cargo forward along the secretory pathway

A

COPII coated vesicles

38
Q

describe the function of COP1 coated vesicles

A

bud from the ERGIS or Golgi. It is the coat protein on vesicles moving from one Golgi cisternae to another during secretion and on the retrieval vesicles that return resident ER proteins marked with KDEL signals

39
Q

what are Clathrin coated vesicles responsible for

A

uptake of extracellular molecules from the plasma membrane by endocytosis and transport of molecules from the trans Golgi network to endosomes, lysosomes or the plasma membrane

Med 103 (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions