Actin Polymerization Flashcards
How does Cytochalasin affect Actin Polymerization?
Binding to the barbed end, blocks elongation therefore impairing movements like cell division
How does Phalloidin affect Actin Polymerization?
Binds to actin filaments and does not allow dissociation
Which drug causes blocking of elongation?
Phalloidin
Spectrin
In RBCs, binds cortical cytoskeleton to plasma membrane
Dystrophin
Binds cortical cytoskeleton to plasma membrane
Which two actin binding proteins binds cortical cytoskeleton to plasma membrane?
Spectrin and Dystrophin
Villin and Fimbrin
Cross-links in microvilli
Calmodulin and Myosin I
Cross-links actin to plasma membrane in microvilli
Beta-Actinin
Cross-links stress fibers and connects actin to protein-plasma membrane complex complexes
Filamin
Cross links actin at wide angles to form screen like gels
What are seven actin-binding molecules that control treadmilling?
Thymosin, Profilin, Gelsolin, Cofilin, Arp2/3, Phalloidin and Latrunculins
Thymosin
Captures actin monomers, prevents monomers from being polymerized.
Profilin
Binds to actin monomers, prevents monomers from being polymerized. BUT, also facilitates exchange of bound ADP for ATP..favoring polymerization.
What does Thymosin and Profilin have in common?
Binds to actin monomers, prevents monomers from being polymerized
Gelsolin
Destabilizes F-actin and caps actin filaments, preventing loss and addition of G-actin.
In presence of Ca, fragments actin filament and remains bound to plus end.
Cofilin
Triggers depolymerization of ADP bound actin at minus end
Arp2/3
Initiates growth f-actin from sides of existing filament-causes branching
Phalloidin
Prevents depolymerization by binding to actin filaments
Latrunculin
Binds to G-actin and induces F-actin depolymerization
What 4 acting binding molecules control depolymerization of the treadmilling?
Cofilin, Arp2/3, Phalloidin and Latrunculins
From smallest to largest (5), what is the assembly labels for intermediate filaments?
Monomer–>dimer—>Tetramer—>Protofilaments–>Filaments
Unlike Actin Filament formation, microtubule formation utilizes energy in the form of ?
GTP
Put protofilaments, dimers and microtubules in order from simplest to more complex
Tubulin Dimers–> Protofilaments–>Microtubules
What are 7 functions of a cytoskeleton?
Cytokinesis, cell support/strength, cell movement, phagocytosis, mitotic spindle formation, cell to cell/cell to extracellular matrix adherence and changes in cell shape.
