ATP Hydrolysis and Cross-Bridge Detachment
Details the role of ATP in detaching the myosin head from actin and re-energizing it for the next cycle of cross-bridge formation.
What is ATP Hydrolysis and Cross-Bridge Detachment?
The repeating sequence of events that causes a muscle fiber to contract, involving the binding and detachment of myosin heads to actin filaments, powered by ATP.
Key points
- Explain the role of ATP in the detachment of myosin from actin.
- Describe the process of ATP hydrolysis and its consequence on the myosin head.
- Relate ATP hydrolysis to the re-cocking of the myosin head.
- Understand the cyclical nature of cross-bridge formation and detachment.
Common exam trap
Confusing ATP hydrolysis with ATP binding for detachment.
Definitions
- Term
Cross-bridge cycle
- Meaning
The repeating sequence of events that causes a muscle fiber to contract, involving the binding and detachment of myosin heads to actin filaments, powered by ATP.
- Term
Rigor state
- Meaning
A state where the myosin head remains tightly bound to the actin filament, typically occurring in the absence of ATP.
- Term
Myosin ATPase
- Meaning
An enzyme activity inherent to the myosin head that catalyzes the hydrolysis of ATP to ADP and Π, releasing energy.
Learning objectives
Explain the role of ATP in the detachment of myosin from actin.
Describe the process of ATP hydrolysis and its consequence on the myosin head.
Relate ATP hydrolysis to the re-cocking of the myosin head.
Understand the cyclical nature of cross-bridge formation and detachment.
Prerequisites
Sliding Filament Theory of Muscle Contraction
Structure of Actin and Myosin Filaments
Role of Calcium Ions in Muscle Contraction
Basic understanding of ATP as an energy currency
Common mistakes
Confusing ATP hydrolysis with ATP binding for detachment.
Forgetting the role of calcium ions in initiating the cycle.
Assuming myosin remains detached after the power stroke without ATP.
Keywords
ATP hydrolysis
Cross-bridge detachment
Myosin head
Actin
Muscle contraction
Sliding filament theory
ATP binding
Re-cocking
Rigor state
Myosin ATPase
Practice preview
The energy released from the hydrolysis of ATP is primarily used for which of the following in the cross-bridge cycle?…
easy
What is the primary role of ATP hydrolysis in the mechanism of muscle contraction?…
easy
During muscle contraction, the detachment of the myosin head from actin is triggered by:…
medium