L1: cytoskeleton part 3

Question 1

post translational modification?

Answer 1

Microtubules are regulated by post-translational modifications (PTMs) of tubulin.
✔ Tubulin’s C-terminal tail is accessible for PTMs, which affect microtubule stability and interactions with microtubule-associated proteins (MAPs) and motor proteins (e.g., kinesin, dynein). phosphorylation,

polyglutamylation: influences interactions with maps. adds glutamate to c erminal tails of tubulin and influences intracellular transport.
detyrosination: stabilises micrtotubules and prevents dissassesmbly by kinesin-13
acetylation: of alpha tubulin. stabilises microtubules good for neurons.
polyglycation: adds glycine to tubulin. in cillia and flagella. stabilises microtubules.

Question 2

drugs?

Answer 2

colchicine/calcemid: binds tubulin and inhibits polymerisation
Nocodazole: depolymerises microtubules.
taxol: stabilises microtubules. intercalate witha alpha and beta dimers.

Question 3

intermediate filaments?

Answer 3

not polarised so no motor proteins. required for structural stability especially in mechanical cells, muscle cells, keratinocytes.

Question 4

where are intermediate filaments?

Answer 4

keratins: in epithelial cells. made up of acidic and basic dimer
disease: brittle hair, blistering skin, liver cirrhosis
vimetinin: mesenchymal cells e.g: fibroblasts.
dermin: muscle cells
GFAP: glial cels
disease: cardomyopathy
neurofilaments: neurons
lamins: nuclear
disease: muscular dystrophy, cardomyopath

Question 5

regulation?

Answer 5

regulation by post translational modification. phosphorylation —-> cell migration, growth, disease states, cell stress (apoptsis), axonal properties (stability of neurons), muscle atrophy, breakdown of thin filaments.

lamins—> chromatin association with nuclear lamina -LAD (lamina associated domains). causes low gene expression.