Tropomyosin. When Ca2+ ion is not bound to troponin, tropomyosin covers the active site on G(lobular) actin. Answered by, DLT.
titin
Tropomyosin and Troponin
Troponin
calcium
The thick filament is composed of the myosin molecule. The thin filament is composed of the actin molecule. Flexing the head of myosin provides the powerstroke.
Actin is a globular molecule
calcium
The tropomyosin molecule blocks the active sites of the actin. Troponin is a molecule that is bound to the tropomyosin. Troponin needs CA+ (calcium ions) to bind to it in order to rotate the tropomyosin molecule and expose the actin molecules for the myosin heads to interact for muscle contraction.
Actin
In addition to providing structural support, actin filaments are involved in movement when they interact with the specialized protein myosin. Myosin is a motor protein that converts the chemical energy in ATP into the mechanical work of movement. The interaction between actin and myosin that produces movement: When ATP binds to themyosin and is then hydrolyzed to ADP, the "head" region of the myosin molecule binds to the actin filament on the slide. The movement of this protein causes the ctin filament to slide. This type of movement is analogous to a line of people who are passing along a long log or pole, the people are myosin molecules; the log is the is the actin.
actin and myosin?
titin
The thin myofilament of skeletal muscles is made of the globular protein called actin.
actin filaments
Tropomyosin and Troponin
actin
ATP