Cytoskeleton

Question 1

Arp2/3

Answer 1

binds to filaments near +/barbed end to facilitate branching.

Question 2

cytochalasin B and D

Answer 2

fungal toxin that binds to + end to block elongation and causing degradation.

Question 3

Rho proteins

Answer 3

are activated by membrane receptors that sense the chemical environment of the cell (leading to chemotaxis). These Rho proteins activate WASP family proteins which stimulate ARP2/3 to allow greater polymerization and ranching of actin which results in pseudopodia formation

Question 4

Phallotoxin

Answer 4

(phalloidin)- binds to AF’s to prevent dissociation into G actin, stabilizes AF; can be used with fluorescent conjugates to label F-actin

Question 5

Cofilin

Answer 5

binds to AF to increase dissociation from - end and stays bound to ADP-actin monomers, preventing reassembly, but profilin can stimulate ADP to ATP exchange, so can allow repolymerization