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Molecular Exam 2 > Zaidi Lecture 9/26 Trafficking > Flashcards

Zaidi Lecture 9/26 Trafficking Flashcards

1
Q

How are proteins and other biomolecules transported throughout the cell?

A

transport vesicles

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2
Q

How do the proteins and biomolecules get from one compartment to another?

A

Bud off and fuse with the next one

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3
Q

What are the contents of a vesicle called?

A

cargo

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4
Q

In vesicular trafficking, is transport directional or bidirectional, and why?

A

directional; because all of the proteins know where they are destined to go

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5
Q

What are the two aspects of the cell that help to provide cues for the incoming traffic?

A

The composition of the membrane and the molecular markers on the membrane surface

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6
Q

What returns the molecules to its original source?

A

Retrieval pathways

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7
Q

What are the 2 functions of the coat on the outside of the vesicles?

A
  1. concentrates are able to select proteins

2. coat is able to mold the vesicle and give it a shape

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8
Q

True or False: The coat on the vesicle remains surrounding the vesicle all the way through fusion to the target cell

A

False

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9
Q

Where does COPI transport from?

A

Golgi

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10
Q

Where does COPII transport from?

A

ER

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11
Q

Where does the Clathrin-coated vesicles mediate transport from?

A

Golgi apparatus and the plasma membrane

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12
Q

Describe the structure of the clathrin subunit

A

there are 3 large and 3 small polypeptide chans that for a triskelion

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13
Q

Describe what triskelions assemble into

A

A basket like structure of hexagons and pentagons that form coated puts

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14
Q

Describe the assembly and disassembly of the clathrin coat

A
  1. The adaptor proteins (which help to trap ish inside of the vesicle) bind to the receptors on the cell, and cause a curvature of the membrane
  2. The membrane continues to bubble out
  3. Membrane bending and fission proteins come to the cell and “snip” the vesicle loose
  4. the adaptor proteins leave and the transport vesicle is naked heyooooo
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15
Q

What is one of the reasons why phosphoinositides play a major role in the coat assembly?

A

They are able to undergo phosphorylation and dephosphorylation to form a variety of derivatives

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16
Q

How do organelles “code” for one membrane domain or another in regards to transport vesicles?

A

They have their own sets of PI kinases and phosphates that allow for interconversion of the phosphoinositides to make the vesicle more organelle specific

Headgroups are specific

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17
Q

What does the head group of a PI serve as?

A

The signature, it is what the kinases and the recognition particles on the organelle look for

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18
Q

What is the function of the BAR domains?

A

Membrane bending proteins

19
Q

Describe the removal of the clathrin coat.

A
  1. protein called dynamin assembles a ring around it
  2. pinching allows the 2 cystolic sides of the membrane to come together and fuse
  3. dynamin recruits other proteins that distort the lipid bilayer by changing the composition of the lipids
  4. vesicles loses its coat
  5. HSP70 protein uses ATP to peel off the coat
20
Q

What are the two domains that are present within dynamin and what are their functions?

A

PIP2 binding domain- tethers the protein to the membrane

GTPase domain-regulates the rate of the vesicle pinching

21
Q

What are the two major proteins that are involved in vesicle targeting?

A

SNARE and Rab

22
Q

Define Rab proteins

A

direct the vesicle to spots on the membrane: active and inactive forms when attached to GTP/GDP like the Ran

23
Q

Define SNARE proteins

A

mediate the fusion of the vesicle with the membrane

catalyze the interaction of the vesicles with the membrane

24
Q

What is the soluble form of the Rab protein?

A

When the Rab is bound to the Rab-GDP dissociation inhibitor (GDI), it is kept in the inactive form

25
Q

What happens when the Rab is bound to the Rab GEF?

A

It is placed and kept in its active form, Rab-ATP and is tightly bound to the membrane

26
Q

Where is Rab1 located?

A

ER and Golgi

27
Q

Where is Rib 3A located?

A

synaptic vesicles and secretory vesicles

28
Q

Where is Rab5 located?

A

Early endoscopes, plasma membrane, and the clathrin coated vesicles

29
Q

Where are v-SNAREs found?

A

on the vesicle membrane

30
Q

Where are t-SNAREs found?

A

On the target membrane

31
Q

How do the t and v SNARE forms interact? What does this do?

A

They wrap around each other and form a bundle; lock the two membranes together

32
Q

What is the enzyme that allows the SNARE bundle to unravel?

A

NSF USES ATP

33
Q

Briefly describe the transport from the ER

A
  1. newly synthesized proteins are packaged into the COP2 coated vesicles
  2. bud off from the ER exit sites
  3. Proteins have exit signals that are recognized by receptors
34
Q

What are the 2 chaperone proteins that are involved in quality control of the proteins leaving the ER?

A

BiP and calnexin

35
Q

Define homotypic

A

fusion with vesicles from the same compartment

36
Q

Define heterotypic

A

fusion with vesicles from different compartments

37
Q

What are fused structures called?

A

vesicular tubular clusters

38
Q

Describe the retrieval pathway of a protein to the ER

A
  1. large vesicles bud off to form smaller vesicles

2. ER retrieval signals direct the proteins

39
Q

What does the KKXX sequence do?

A

present in the ER membrane proteins and interacts with the COPI and is packaged into a COPI coated vesicles

40
Q

What does the KDEL sequence do?

A

It recognizes the soluble proteins and packages everything into a COPI coated vesicle

41
Q

What does the cis side of the golgi face?

A

The ER

42
Q

What does the trans side of the golgi face?

A

The plasma membrane

43
Q

Define the Golgi Apparatus

A

collection of flat, membrane enclosed compartments(cisternae)

44
Q

What is the function of the golgi apparatus?

A

protein glycosylation

Molecular Exam 2 (13 decks)

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