Cytoskeleton Flashcards
Cytoskeleton Roles (5)
Cellular polarity & shape Directional migration Formation of mitotic/meiotic spindle Chromosome segregation Cytokinesis
Cytoskeleton components:
Intermediate filaments
Actin
Microtubules
Intermediate Filaments location (4)
Surround nucleus
Extend to cell periphery
At cell-cell junctions
At cell-ECM junctions
Intermediate Filaments Structure
2 chained coiled coil that forms an antiparallel tetramer
Examples of Intermediate Filaments(3)
Keratin
Neurofilaments
Nuclear lamins
Intermediate Filaments
Controlled by phosphorylation (dynamic)
Role in signaling and controlling gene regulatory networks
Actin Filaments
Polymers of actin with ATP or ADP bound
Helical
Polar (barbed and pointed end)
Microtubules
Polar
Binds GDP or GTP
Polymers of alpha/beta tubulin arranged in tubules with 13 protofilaments
Microtubule examples (5)
Mitotic spindle Cilia Flagella Basal bodies Centrioles
ATP/GTP cap
At growing end
Due to nucleotide hydrolysis lagging behind polymerization
Phalloidin (natural toxin)
Bind and stabilize actin filaments
Colchicine (natural toxin)
Depolymerize microtubules
Taxol (natural toxin)
Bind and stabilize microtubules
Microtubule growth stabilized by ______ and destabilized by _____ which leads to _________
Stabilize: GTP tubulin cap at + end
Destabilize: GDP tubulin at + end
Leads to: rapid depolymerization
+ tip proteins
Inhibit catastrophes to let microtubules get to cell periphery
Primary cilium
Non-motile sensory organelles
Role in developmental signaling pathways
MAPs
Microtubule Associated Proteins
MAPs regulate __________ and can ________
Microtubule assembly
Stabilize or destabilize the + and - end
Actin polymerization provides
Force for movement
How to get force for movement (3)
Nucleation more actin filaments
Sever existing filaments to create more barbed ends
Form branches from existing actin filaments
Are 2/3 is activated by ______ and is required for _______
Rho (downstream)
Nucleation of actin polymerization
Are 2/3 involved with (3)
Wound healing
Neutrophil migration
Invasion of metastatic cancer cells
Cytoskeletal Motors
Myosin (actin)
Kinesin (microtubule)
Dynein (microtubule)
Cytoskeletal motors are all ________
ATPases
Create conformational change by binding ATP to make mechanical work
Myosin V
Carries cargos on tail
Myosin I
Single headed myosins
Bind to plasma membrane
Myosin II
Form bipolar filaments
Each power stroke moves myosin 1 actin subunit closer to + end
Filament that forms myosin
Myosin moves towards
+ end of actin
Myosin roles (3)
Cytokinesis
Intracellular transport
Endocytosis
Myosin globular head has _______ and the tail binds to _______ and is ______
ATPase
Membrane/target
Variable
Kinesin moves towards
+ end of microtubule
Kinesin head has ______, the tail binds _______ and is _______, the neck region determines _________
ATPase
Target
Variable
Polarity (next to head)
Dynein moves towards
- end of microtubule
Dynein is found in
Cilia and flagella arms for beating
Primary Ciliary Dyskinesia (PCD)
Cilia are immobile
Male sterility and respiratory tract infection
Mutation in outer arm ciliary dynein heavy chain
Dynein is used for
Retrograde axonal transport
Transporting vesicles
Involves dynein, kinesin, myosin V
Transfer from microtubule to actin
Intracellular transport from _____ to ______
ER to cell periphery (and back)
Intracellular transport occurs on ______ via _______
+ end of microtubule
+ tip protein to prevent catastrophe
Melanosomes need ______ to be transported to ______
Myosin V
Cell periphery
In melanosomes, myosin V binds cargo using _______
Melanophilin and Rab-GTP
Rab-GTP binds to receptor on cargo
Griscelli Type 1
Mutation in myosin V, melanophillin or Rab-GTP
Silver hair, light skin, neuro defects
