Microtubule Function Flashcards
1
Q
Motor proteins require __
A
ATP
2
Q
Axonal Transport
A
Squid Axons (model system)
- radioactive aa injected
- proteins move along MT
- SDS-PAGE
labelled proteins travel at different speeds in cell
3
Q
Kinesin
A
MT (+) end directed motor protein
- 2 heavy chains = head, neck, stalk (ATPase and MT binding)
- 2 light chains = recognize cargo
4
Q
Functions of Kinesin
A
Organelle Transport
- Kinesin-1 = 2 heavy + 2 light
- Kinesin-2 = 2 heavy (heterotrimeric)
Sliding
- Kinesin-5 = 4 heavy (bipolar)
Disassembly
- Kinesin-13 = 2 heavy – head+neck
5
Q
Cargo Movement
A
- cargo need appropriate receptor that is recognized by specific light chain
6
Q
Movement of Kinesin
A
- anterograde
- kinesin btwn αβ dimer
- ATP hydrolysis –> kinesin has conformational change (head moves 16nm)
- linker swing forward + dock head = power stroke
7
Q
Cytoplasmic Dynein
A
MT (-) end directed motor protein
- heavy chains = ATPase activity + stalk
- linker interact with dynactin complex – bind cargo
- ATP hydrolysis = drive movement
8
Q
Dynactin Complex
A
- links dynein to cargo
- regulated by dynamitin (release cargo)
- p150glued binds MTs
9
Q
Post-translational Modification of Tubulin
A
- acetylation of a lysine residue of α tubulin
- stabilize MT
10
Q
Cilia vs Flagella
A
Cilia = 2-10μm Flagella = 10-2000μm
11
Q
Axoneme
A
- 9+2 array of microtubules
- outer doublets — A and B tubules held with nexin
- axonemal dynein (stem - A tubule) (head reach to B tubule)
12
Q
Axoneme and Basal Body
A
- 9 basal body triplet MTs
- A and B tubule pass transition zone. C tubule does not
13
Q
Axoneme Bending
A
- sliding MT against each other
- NO nexin = dynein moves to (-) end + MTs slide
- Nexin = bending + no sliding
14
Q
Intraflagellar Transport
A
- moves material “up and down”
- uses cytoplasmic dynein
15
Q
Interphase Cells
A
Contain a non-motile primary cilium
- axonemal structure
- no axonemal dynein
