In this photo, I know that the arrows pointing towards the M-line of sarcomere on actin filaments are due to the power strokes of myosin heads. However, what I don't understand are the arrows on the myosin filaments pointing away from the M-line.

Are they the reaction forces (action-reaction pair, where the action force is power stroke)? Also, will this force (pointing away from M-line) 'tear apart' the myosin filaments on M-line? If not, how can the filament withstand this force?


1 Answer 1

  1. Yes, they are action-reaction pair.( Newton’s third law).
  2. No, it won’t tear under normal circumstances. The filament withstands all that force because the attractive force between its constituents is far more than the force generated by myosin actin cycle.
  • $\begingroup$ Thank a lot. For (2), for the attractive force, do you mean the force between the myosin filament and the M-disc? $\endgroup$
    – 234ff
    Sep 28, 2020 at 1:49
  • 1
    $\begingroup$ @234ff yes. That’s it. $\endgroup$
    – JM97
    Sep 28, 2020 at 1:53

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