Review

• Actin polymerization


  Begins by forming a small cluster consisting of three actin monomers, called nucleation
• Actin binding proteins


  Regulate actin polymerization by binding to a filament's end and blocking subunit addition and loss
• Energy source for motor proteins

  ATP hydrolysis
• Microtubule-organizing center in animal cells

  The centrosome
• Cytoskeletal filaments that form local extensions of the plasma membrane

  Actin filaments
• Function of non-mitotic kinesin motor proteins


  Intracellular transport (towards the plus end of microtubules)
• Dynein motor proteins that power the beating of cilia and flagella

  Axonemal dyneins
• Microtubule-based structure that acts as antennae sensing extracellular signals


  Primary cilia
• Main role of γ-tubulin ring complex in the centrosome

  It acts as a seed for rapid microtubule growth
• Spindle microtubules that help chromosomes move toward the spindle poles in Anaphase A

  Kinetochore microtubules
• Part of intermediate filament structure that determines their specific functions

  The variable head and tail domains
• Cytoskeletal filament dynamic shown in the figure


  Actin treadmilling
• How the leading edge extends

  The extension of the leading edge involves the branching and polymerization of actin filaments