Actin Microfilaments and Motor Proteins

  1. Similarities and Differences

    • Similarities:

      • All are motor proteins that move along cytoskeletal fibers.

    • Differences:

      • Dynein: Moves along microtubules towards the minus (-) end.

      • Kinesin: Moves toward the plus (+) end of microtubules.

      • Myosin: Primarily interacts with actin filaments.

  2. Structural Features of Kinesin

    • Kinesin has a motor domain that varies, which determines its specific functions.

    • Structural similarities and variations enable kinesin to adapt for different cellular roles.

  3. Power of Motor Proteins

    • Motor proteins are powered by ATP hydrolysis, which energizes their movements.

  4. Situations for Movement of Cytoskeletal Fibers

    • Motor proteins can move cytoskeletal fibers to facilitate the transport of organelles or molecular cargo (anterograde and retrograde transport). They can also help organize these cytoskeletal fibers into structured arrays.

  5. Structural Features Shared by Kinesin and Myosin

    • Both share a motor domain essential for movement along their respective filament types (microtubules for kinesin and actin for myosin).

  6. Processive Motility

    • Defined as the ability of motor proteins to take multiple steps along a filament before detaching.

    • Kinesin is known for processive motility, allowing efficient transport.