Motors, Actin, Cell Motility (Actin)

Question 1

Phalloidin

Answer 1

• Belongs to a class of toxins
  called phallotoxins, which are found in the death cap mushroom
• Phalloidin is lethal after a few days when injected into the bloodstream.
• The major symptom of phalloidin
  poisoning is acute hunger due to the destruction of liver
  cells.
• It functions by binding and stabilizing filamentous
  actin (F-actin) and effectively prevents the depolymerization of actin fibers.

Question 2

Actin Nucleation by the Arp2/3 Complex

Answer 2

• The Arp2/3 complex helps in the creation of branch points for
  the polymerization of new actin fibers.

-F-actin networks are highly branched.

-Arp2/3 complex starts polymerization at branch points

-Polymerization and branching play a central role in directed cell motility

Question 3

Directed cell motility

Answer 3

• Coordinated activity of actin binding proteins controls microfilament formation in a lamellipodium to allow directed cell movement
• A lamellipodium is an actin projection on the leading edge of a cell