The Cytoskeleton Flashcards
How big are actin filaments, intermediate filaments and MTs?
7, 10 and 25nms
Where do MTs grow out of?
The MT organising centre which contains two centrioles.
What are MTs made out of?
a and B tubulin dimers.
What is the +end?
B-tubulin, the fast-growing end, towards the plasma membrane
What is the -end?
a-tubulin, the slow-growing end, from the MTOC.
How is tubulin post-translationally modified?
Detyrosination (EEY–> Y removed)
Acetylation at K40
Polyglutamylation (addition of multiple E residues)
What adds to the +end?
GTP-tubulin subunits, when the GTP cap is lost the MT depolymerises (catastrophe)
What are the motor proteins called?
Kinesin and Dynein
Which motor proteins migrate to which ends?
Kinesin walks to the +end powered by ATP hydrolysis
What does cytoplasmic dynein need for trafficking?
Dydactin
Which viruses does dynein bind to?
Adenovirus, herpes and HIV-1
which viruses does Kinesin bind to?
Vaccinia and herpes
What do MAPs do?
Stabilise and destabilise MT to make more efficient trafficking
Name 3 MAPs
Tau, MAP2 and spastin
When does Tau detach?
When phosphorylated
What is spastin?
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
What do multiple dyneins in motile cilia do?
cause bending
What forms a motile cilia?
9 pairs of dynein + 2 in the centriole
How do defects in Tau result in Alzheimer’s?
Hyperphosphorylation results in detachment, aggregation and formation of neurofibrilliary tangles.
What is caused by mutations in spastin?
Spastic paraplegia, autosomal dominant, progressive lower limb spasticity and degregation of spinal neurones.
What causes Lissencephaly?
Mutation in a-tubulin - smooth brain and small head.
What do N256S abd K253N do in hereditary spastic paraplegia?
reduce velocity of movement
What do R280S and K25N do in HSP?
Reduce binding to MTs when attached to cargo.
What mutation causes Chacot-Marie-Tooth disease type 2A?
Kif1BB trafficking of mitochondria in neurones.
What do Paclitaxel and Docetaxol do?
Stabilise MTs - affects cell proliferation
What does Taxol do?
Induce mitotic arrest and increases the number of abnormal spindles
What does Monastrol do?
Inhibits E5G which makes the MTs slide apart from the spindle
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)
