Cytoskeleton 1 Flashcards
What is the cytoskeleton?
Scaffold and structure framework responsible for cell movement.
-actin, intermediate filaments, and microtubules
G actin
Monomers with binding sites for other G actin. Dimer and trimer formation called nucleation.
F actin
Monomers of g actin added together in elongation step.
Monomers add to
Barbed (+) end.
Requires ATP
Monomers removed from
Pointed (-) end
Requires Pi release
Steady state
Rate of assembly = rate of disassembly
Treadmilling
Addition and subtraction at same time leaving filament length unchanged
Formin
Binds to actin monomers, facilitating nucleation by adding monomers until it’s released.
Arp2/3
Binds near barbed end and initiates branch formation, stays bound.
ADF/cofilin
Binds to ADP actin at pointed end, enhancing dissociation rate and prevents filament binding.
Profilin
Increases exchange of ADP for ATP on G actin monomers, stimulating filament formation
CapZ
Binds to + end inhibiting polymerizatiom
Troomodulin
Binds to - end preventing dissociation of actin
Fimbrin
Holds two actin filaments in parallel using Ca2+ to aid. Supports plasma membrane
a-actinin
Holds 2 filaments together so they can contract, held further apart
Spacer domain
Filamin
Cross links actin in NETWORK. Supports cell surface
Cell migration
Filopodia (filaments) go first followed by lamellopodia (actin bundles)
WASP/Scar complex
Activated Arp2/3
Barbed end tracking proteins
Connect growing actin filaments to plasma membrane
Wiskott Aldrich Syndrome
Inherited immunodeficiency disease, white blood cells disrupted and bleed easily due to mutation in WASP protein (doesn’t activate Arp2/3 for branching)
Twinfilin
Carries to barbed end
