Regulation of Muscle Contraction Flashcards
The availability of what binding sites on actin are regulated by troponin and tropomyosin?
Myosin-binding sites
Why does the regulation of myosin-binding sites by troponin and tropomyosin occur?
This avoids the continuous muscle contraction and saves energy
What does the release of Ca2+ triggered by nerve impulse cause?
It causes conformational changes to tropomyosin-troponin complex exposing myosin-binding sites
What is the first step in the Calcium control and muscle contraction?
Ca2+ binds to the troponin which then uncovers myosin binding sites on actin thin filaments
What does the binding of Ca2+ to troponin do?
Uncovers the myosin binding sites on actin thin filaments
What is the second step in the Calcium control and muscle contraction?
Inorganic phosphate (Pi) release induces the power stroke, which pulls the actin filament about 70A toward the center
What is the role of inorganic phosphate?
The release of it induces the power stroke
What is the power stroke?
An action which pulls the actin filament about 70 A towards the center
What is the third step in the Calcium control and muscle contraction?
ADP release empties the nucleotide binding site in myosin
What is the fourth step in the Calcium control and muscle contraction?
ATP binds to the myosin which causes the myosin to dissociate from actin
What is the role of ADP?
It releases from the myosin which leaves the nucleotide binding site open for ATP
What is the role of ATP?
It binds to the myosin after ADP leaves, which initiates the release of the myosin from the actin filament
What is the fifth step in the Calcium control and muscle contraction?
ATP hydrolysis induces the recovery conformation
What actually causes muscle contraction?
Relative movement of filaments
