Motors, Actin, Cell Motility Flashcards
Tauopathies
Defect in Tau biology associated with Alzheimer’s disease, as well as other forms of neurodegenerative disorder
MT-Associated Motor proteins
- Power intracellular transport
-Two main types—kinesin and dynein.
- Use ATP to generate force.
- Can move material along MT track.
- Can generate sliding force between MTs
Kinesin
Plus ended direction
Dynein
Minus end direction
Motor Proteins and Movement
- ATP binding to the leading head induces a conformational change
that swings the trailing head 180º towards the (+) end of the
microtubule. This is the force-generating step. - The new leading head quickly binds to a tubulin subunit and releases its ADP, moving
the kinesin’s cargo forward. - In the trailing head, ATP is hydrolyzed to
ADP, which leads to detachment from the microtubule. - ATP binds to the leading head to repeat
the reaction cycle.
Kinesin and Dynein
at Work in Zebrafish
Embryos
- Survival mechanism that re-
distribute melanin granules for
camouflage - In the dark, melanin granules are
dispersed outward by kinesin,
causing the embryo to be darkly
colored - In the light, melanin granules are
aggregated toward the center by
dynein, causing the embryo to be
lightly colored
Microtubule-Organizing Center
- Central site of MT assembly
- Only found in eukaryotic cells.
The two most important types of MTOCs
1) the basal bodies associated with cilia and flagella
2) the centrosome associated with
spindle formation.
Cytoskeleton
Made up of microtubules, microfilaments and intermediate filaments
Microtubules
-Hollow tube formed from tubulin dimers
Microfilaments
Double helix of actin monomers
Intermediate filaments
Strong fiber composed of intermediate filament protein subunits
