Membrane Fusion Flashcards Preview

Thanh Cell Physiology Unit III > Membrane Fusion > Flashcards

Flashcards in Membrane Fusion Deck (10)
Loading flashcards...
1
Q

Is membrane fusion thermodynamically favorable or unfavorable?

A

Unfavorable - highly inefficient

- need machinery!

2
Q

Name 2 molecular motor proteins and where they direct vesicles

A

dynein - to golgi
kinesin - away from golgi

helps deliver vesicle to fusion site via actin/tubule tract

3
Q

What proteins aid membrane fusion?

A

SNARE (soluble NSF attachment protein receptor)

4
Q

3 classes of SNARE proteins and where they are located

A
  1. syntaxin
    • target membrane
  2. (VAMPS) - vesicle associated membrane protein
    • transport vesicle
  3. (SNAPS) - synaptosome associated protein
    • target membrane

all 3 associate (coiled coil) during membrane fusion

5
Q
structure of:
1. syntaxin
2. VAMPS
3. SNAPS
(recall figure from lecture)
A
  1. 3 amphipatic helices, huge helical domain, transmembrane domain
  2. 2 huge helical domains sandwiched by CCCC
  3. huge helical domain, transmembrane domain
6
Q

Describe the disassembly of SNARE complex

A

after fusion, cell needs to recycle SNARE proteins for more fusion events

NSF binds to complex, uses 6 ATP hydrolysis to disassemble 1 SNARE complex (unwinds coiled coil)

7
Q

Sec1 protein function

A

after disassembly of SNARE complex, proteins needs to be unwound and changed into active conformation

8
Q

Viral mediated membrane fusion steps

A

enveloped virus uses membrane fusion to infect cells

  1. prefusion
  2. extended intermediate
  3. collapse of intermediate
  4. hemifusion
  5. fusionpore (post fusion)
9
Q

structure of viral fusion proteins

A

1 transmembrane domain (inserted into viral membrane)

1 hydrophobic fusion domain (hidden in viral protein)
- inserted into target cell membrane and collapses with signal and fusion

10
Q

What causes viral fusion of influenza?

A

Drop in pH = viral envelop fuse