The Cytoskeleton Flashcards

1
Q

How big are actin filaments, intermediate filaments and MTs?

A

7, 10 and 25nms

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2
Q

Where do MTs grow out of?

A

The MT organising centre which contains two centrioles.

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3
Q

What are MTs made out of?

A

a and B tubulin dimers.

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4
Q

What is the +end?

A

B-tubulin, the fast-growing end, towards the plasma membrane

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5
Q

What is the -end?

A

a-tubulin, the slow-growing end, from the MTOC.

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6
Q

How is tubulin post-translationally modified?

A

Detyrosination (EEY–> Y removed)
Acetylation at K40
Polyglutamylation (addition of multiple E residues)

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7
Q

What adds to the +end?

A

GTP-tubulin subunits, when the GTP cap is lost the MT depolymerises (catastrophe)

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8
Q

What are the motor proteins called?

A

Kinesin and Dynein

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9
Q

Which motor proteins migrate to which ends?

A

Kinesin walks to the +end powered by ATP hydrolysis

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10
Q

What does cytoplasmic dynein need for trafficking?

A

Dydactin

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11
Q

Which viruses does dynein bind to?

A

Adenovirus, herpes and HIV-1

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12
Q

which viruses does Kinesin bind to?

A

Vaccinia and herpes

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13
Q

What do MAPs do?

A

Stabilise and destabilise MT to make more efficient trafficking

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14
Q

Name 3 MAPs

A

Tau, MAP2 and spastin

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15
Q

When does Tau detach?

A

When phosphorylated

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16
Q

What is spastin?

A

A member of the AAA protein family, attaches to the C-terminal tubulin tails and dislodges them from the MT lattice stimulated by MT polyglutamylation

17
Q

What do multiple dyneins in motile cilia do?

A

cause bending

18
Q

What forms a motile cilia?

A

9 pairs of dynein + 2 in the centriole

19
Q

How do defects in Tau result in Alzheimer’s?

A

Hyperphosphorylation results in detachment, aggregation and formation of neurofibrilliary tangles.

20
Q

What is caused by mutations in spastin?

A

Spastic paraplegia, autosomal dominant, progressive lower limb spasticity and degregation of spinal neurones.

21
Q

What causes Lissencephaly?

A

Mutation in a-tubulin - smooth brain and small head.

22
Q

What do N256S abd K253N do in hereditary spastic paraplegia?

A

reduce velocity of movement

23
Q

What do R280S and K25N do in HSP?

A

Reduce binding to MTs when attached to cargo.

24
Q

What mutation causes Chacot-Marie-Tooth disease type 2A?

A

Kif1BB trafficking of mitochondria in neurones.

25
What do Paclitaxel and Docetaxol do?
Stabilise MTs - affects cell proliferation
26
What does Taxol do?
Induce mitotic arrest and increases the number of abnormal spindles
27
What does Monastrol do?
Inhibits E5G which makes the MTs slide apart from the spindle
28
What is affected in ciliary dyskinesia?
Mutations in dynein heavy chain - heart is on the right side of the chest due to missing cilia in the early embryo (no L/R gradient)