Can anyone describe the activities of tropomyosin and tropnin in the contraction of muscles?
OK…see…the point is that Tropomyosin blocks the Myosin binding sites present on Actin and hence preserves the resting state of the muscle (i.e when it is not contracting). Troponin has 3 parts with 3 different functions…one of it binds to tropomysosin and regulates the myosin binding, the other two are involved in regulating the activity of tropomyosin itself. When calcium enters the sarcoplasm (on depolarization of the muscle due to the nerve impulse) the calcium ions bind to troponin and this troponin causes the tropomyosin to slide. This sliding causes the tropomyosin that was covering the myosin binding sites to move out and hence allows myosin to bind to actin…and when this happens the muscle contracts.
