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Cell/Histo - MV > Lecture 4 - Intracellular Trafficking > Flashcards

Lecture 4 - Intracellular Trafficking Flashcards

1
Q

The synthesis of all proteins BEGINS where?

A

On the free ribosomes. IT doesn’t always end on free ribosomes, as they can be directed to the ER after it has been recogonized as one that need to be taken to ER. but it does begin on FREE ribosomes.

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2
Q

2 types of ways/times that Protein can be delivered/translocated to ER?

A

Co translational translocation is when the protein is translated on a membrane bound ribosome (even though it didn’t begin translation there) and while being translated it is being funneled into the lumen of the ER.
Post translational translocation is when the protein is translated on free ribosome and then translocated into the ER lumen.

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3
Q

Does Intercellular trafficking always required membrane bound vesicles?

A

No there are few ways that don’t

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4
Q

Whats important about the integrity of the cell membrane?

A

I can never have penetration of its membrane, or it dies

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5
Q

What are 5 main places the cell transports vesicles to?

A

PM, Mito, Nucleus, lysosomes, Golgi

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6
Q

What is the relationship of Endo and Exo cytosis?

A

There must be a balance so that the PM, doesn’t getter substantially larger or smaller.

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7
Q

2 types of endo cytosis? define

A

Fluid Phase - non selective, vesicles contain extracellular fuild and contents
Receptor mediated - receptors are assoc with coated pits where ligands binding to receptor creates endocytosis response.

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8
Q

What are 5 things Clathrin Coating used in?

A

selective endocytosis
exocytosis
triskeliton subunits that interlock to form geometric shapes
May anchor transmemb receptors at the site of forming vesicle
Adaptins connect the clathrin to the receptor molec.

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9
Q

What unique about After clatherin is done doing its job?

A

It must be removed immediately, so that it can bind to other things. THIS REQUIRES ATP

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10
Q

HSP means? AND what do they do

A

Heat shock proteins, defined on how they were discovered, but actually better termed at chaperone proteins, b/c they do so much more as far as help with folding of proteins.

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11
Q

What are cotamers and what are the 2 main forms?

A

are coated pits and vesicles.
COP1 - coat protein that is on vesicles b/w Golgi stacks
COP2 - coat protein that is on vesicles b/w ER to Golgi

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12
Q

What mediates Clathrin binding to the vesicular membrane?

A

Adaptin

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13
Q

Vesical Fusion is how many steps? and what are they

A

2 steps, Recognition and Fusion

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14
Q

Recogniton of vesicle fusion requires what 2 proteins

A

SNARE -V and SNARE- T vesicle and target

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15
Q

Fusion of vesicle requires what proteins

A

NSF *N ethylmaleimide - sensitive fusion)

SNAP - Soluable NSF attachment protein

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16
Q

Vesicle fusion Sequence of events , 8 steps are?

A
  1. clathrin coat removed, 2. binding of SYNAPSINS TO SPECTRIN
  2. SNARE - v binds Snare - t
  3. SNAP binds sNARE
  4. NSF (ATPase) bind to SNAP
  5. NSF/SNAP complex disassembles SNARE for reuse
  6. Release of NSF and SNAP from SNARE
  7. Initiation of CALCIUM DEPENDENT memb fusion
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17
Q

What is the final step of Vesicle fusion?

A

Ca is required! which requires fusigen.

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18
Q

Proteins bound for lysosomes or export take what pathway?

A

Free ribo - RER - Golgi - Secretory vesicle or lysosome

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19
Q

what is a signal sequence? and is it needed for exported proteins or those that go to lysosome?

A

sequence that attracts an SRP that will stop translation and will get the protein to RER. The SRP docs to cytoplasmic side of ER. Signal seq of the protein Is translocated into ER (through a translocon) and inserted into the LUMEN. The signal protein Is cleaved by a signal peptidase.

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20
Q

What is needed to get a translocated protein into the ER?

A

An HSP 70 keeps the protein unfolded so it will fit through the translocon, another HSP 70 BiP aids in pulling through the channel and folding when through.

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21
Q

Sugar chains are attached to what residue?

A

Asparagine

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22
Q

Which type of glycosylation is done in the ER

A

N linked

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23
Q

What attaches the sugar chain to the ER? and where at on the ER?

A

Dolichol phosphate attaches the sugar to the lumen of the ER.

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24
Q

What are 3 domains of the ER?

A

Smooth, Rough and Transitional ( where vesicles exit to Golgi)

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25
Q

The exocytoplasmic leaflet faces which compartment?

A

luminal compartment

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26
Q

The protoplasmic leaflet faces which compartment?

A

cytosolic compartment?

27
Q

Proteins synthesized on free ribosomes and release into cytosol, are targeted to the ?

A

Nucleus, mito, peroxisomes

28
Q

Proteins for secretion or targeted to the ER, Golgi, lysosomes, or PM, are synthesized on?

A

Ribosomes BOUND to the ER

29
Q

Proteins targeted to Lysomes, golgi, or secretion are transported in vesicles that ?

A

bud off the transitional ER.

30
Q

What are GPI anchors, and what used for?

A

Glycosylphosphatidylinositol is a marker to insert proteins into ER lumen and transported to PM. HOw cell adds new PM.

31
Q

What can the ER do to misfolded proteins?

A

it can direct them to repair or degradation pathways by adding a glucose residue that takes it to calreticulin.

32
Q

What is calreticulin?

A

a chaperone protein that will attempt to refold proteins in the ER.

33
Q

What happens to severely misfolded proteins?

A

sent back through the translocon to be degraded by proteasomes in the cytoplasm

34
Q

Where are phospholipids synthesized?

A

on the CYTOSOLIC SIDE of the ER

35
Q

how do Phospholipids get to the luminal leaflet?

A

Flippase proteins flip the phospholipids to the luminal side.

36
Q

What are Golgi sacs called

A

Cisternae

37
Q

What are the 2 faces of the Golgi and what is order of transport typically?

A

Cis to Trans (former faces nucleus and latter away from nucleus) aka CGN and TGN

38
Q

Whats Golgi responsible for modifying?

A

Carbohydrates attached to the glycoproteins and proteoglycans received from the ER

39
Q

What is the modification of Carbohydrates called?

A

glycosylation

40
Q

Golgi carries out which glycosylation

A

O linked,

41
Q

O-linked glycosylation is addition of Carbs to which AA’s

A

serine and threonin

42
Q

Golgi makes what 2 important membrane components?

A

sphingomyelin and glysocphingolipids

43
Q

movement of vesicles on the Golgi can go both ways? T/F? name (s)_?

A

True, Anterograde, cis 2 trans

Retrograde cis 2 RER.

44
Q

once leave the Trans Golgi, what 4 places can vesicles go?

A

Lysosome, or PM to be membrane bound or PM to be Secreted

45
Q

What are the Two ways of secretion? define?

A

Facultative- held until needed and signaled to be released from containment vesicle in cytoplasm
Constitutive - continuously secreted and no signal needed. like lipids, PM proteins, and Extracellular prots.

46
Q

What is the targeting signal for lysosomal enzymes?

A

mannose 6- phosphate

47
Q

The mannose 6 phosphate are found on glycoproteins that will become?

A

acid hydrolases in lysosomes

48
Q

TGN is responsible for concentrating the labeled glycoproteins into what?

A

transport vesicles

49
Q

Transport vesicles must lose what to bind?

A

clathrin coat, and does so right after leaving the trans golgi

50
Q

What creates Low pH in lysosome? and what is name of this stage of lysosome?

A

hydrogen ion pumps
late lysosome, or secondary
and has fused with phagosome

51
Q

Not everything can be digested, what is left over of secondary lysosome?

A

Residual body

52
Q

Early endosome pH is?

A

7.3-7.4

53
Q

late endosome pH is ?

A

5.0

54
Q

tay sachs disease is what kind of disorder?

A

a lysosomal storage disorder.

55
Q

Proteins bound for the Nucleus are synthesized where? and must have a signal called _______ and found where in the polypeptide?

A

free ribosomes
NLS nuclear localization signal
found anywhere on the polypeptide.

56
Q

What structure of the Nucleus recognizes the NLS? and after it recognizes it, what does it do to the signal/

A

Nuclear pore complex

it leaves it for future use, recycles

57
Q

as far as the transport of newly made protein, how is the mitochondria similar and different than the nucleus?

A

Prots synthesized on free ribosomes in both
Signal seq on prot. bound for Mitochondria are at the N terminal end, and Nuclear bound prots, are anywhere on polypeptide.

58
Q

Which proteins have more signals… ones headed for Nuc, or for mitochondria?

A

for mitochondria, b/c the higher number of membranes, mean more direction to get to their desitnation.

59
Q

What is the name of the comon entry gate of precursor proteins into the mitochondria?

A

TOM, translocase outer mitochondrial memb complex

60
Q

is ATP required for transport across the mito memb. through the TOM complex?

A

Yes

61
Q

HSP 70 and HSP 60, are crucial for getting protein properly to their destination, what again do these HSPs do respectively?

A

70- maintain protein in partially unfolded state prior to entry
60- does final folding one inside mitochondria.

62
Q

The first terminal signal for the mito bound protein is or is not cleaved upon arrival at mito?

A

cleaved. if first its cleaved.

63
Q

motor proteins carry vesicles along MT’s directionally. Towards the terminus of an axon is called? towards the cell body is called? which proteins do these respectively?

A

Anterograde by kinesins. to terminus

Retrograde by dynein, to cell body

Cell/Histo - MV (8 decks)

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