Actin Polymerization

Question 1

How does Cytochalasin affect Actin Polymerization?

Answer 1

Binding to the barbed end, blocks elongation therefore impairing movements like cell division

Question 2

How does Phalloidin affect Actin Polymerization?

Answer 2

Binds to actin filaments and does not allow dissociation

Question 3

Which drug causes blocking of elongation?

Answer 3

Phalloidin

Question 4

Spectrin

Answer 4

In RBCs, binds cortical cytoskeleton to plasma membrane

Question 5

Dystrophin

Answer 5

Binds cortical cytoskeleton to plasma membrane

Question 6

Which two actin binding proteins binds cortical cytoskeleton to plasma membrane?

Answer 6

Spectrin and Dystrophin

Question 7

Villin and Fimbrin

Answer 7

Cross-links in microvilli

Question 8

Calmodulin and Myosin I

Answer 8

Cross-links actin to plasma membrane in microvilli

Question 9

Beta-Actinin

Answer 9

Cross-links stress fibers and connects actin to protein-plasma membrane complex complexes

Question 10

Filamin

Answer 10

Cross links actin at wide angles to form screen like gels

Question 11

What are seven actin-binding molecules that control treadmilling?

Answer 11

Thymosin, Profilin, Gelsolin, Cofilin, Arp2/3, Phalloidin and Latrunculins

Question 12

Thymosin

Answer 12

Captures actin monomers, prevents monomers from being polymerized.

Question 13

Profilin

Answer 13

Binds to actin monomers, prevents monomers from being polymerized. BUT, also facilitates exchange of bound ADP for ATP..favoring polymerization.

Question 14

What does Thymosin and Profilin have in common?

Answer 14

Binds to actin monomers, prevents monomers from being polymerized

Question 15

Gelsolin

Answer 15

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.

Question 16

Cofilin

Answer 16

Triggers depolymerization of ADP bound actin at minus end

Question 17

Arp2/3

Answer 17

Initiates growth f-actin from sides of existing filament-causes branching

Question 18

Phalloidin

Answer 18

Prevents depolymerization by binding to actin filaments

Question 19

Latrunculin

Answer 19

Binds to G-actin and induces F-actin depolymerization

Question 20

What 4 acting binding molecules control depolymerization of the treadmilling?

Answer 20

Cofilin, Arp2/3, Phalloidin and Latrunculins

Question 21

From smallest to largest (5), what is the assembly labels for intermediate filaments?

Answer 21

Monomer–>dimer—>Tetramer—>Protofilaments–>Filaments

Question 22

Unlike Actin Filament formation, microtubule formation utilizes energy in the form of ?

Answer 22

GTP

Question 23

Put protofilaments, dimers and microtubules in order from simplest to more complex

Answer 23

Tubulin Dimers–> Protofilaments–>Microtubules

Question 24

What are 7 functions of a cytoskeleton?

Answer 24

Cytokinesis, cell support/strength, cell movement, phagocytosis, mitotic spindle formation, cell to cell/cell to extracellular matrix adherence and changes in cell shape.