Myosin Filaments

• What do myosin filaments have- heads?


  GLOBULAR heads that are HINGED, so they can move back and fourth
• What does each myosin head have?


  A binding site for actin and a binding site for ATP
• What do actin filaments have?


  Binding sites for myosin heads - called ACTIN-MYOSIN binding sites
• What is found between actin filaments?


  A protein called TROPOMYOSIN
• what does tropomyosin do?


  Helps myofilaments move past each other
• What does tropomyosin block?


  Binding sites in RESTING muscles
• What happens in a resting (unstimulated) muscle?


  The actin-myosin binding site is blocked by tropomyosin

  • so myofilaments cannot slide past each other because the myosin heads cannot bind to the actin-myosin binding site on the actin filaments