Myosin cardiac, full length, from porcine heart

Fully functional.

Tested in actin activated phosphate release assay, motility assay.

Cardiac Myosin: The Motor Protein of the Heart

Cardiac myosin is a specialized motor protein responsible for heart muscle contraction. It is a class II myosin found in cardiomyocytes (heart muscle cells) and plays a crucial role in converting chemical energy from ATP into mechanical force to drive heartbeats.

Key Functions of Cardiac Myosin:

1. Powers Heart Contraction: Generates force by interacting with actin filaments in the sarcomere.

2. ATP Hydrolysis: Acts as an ATPase, breaking down ATP to produce energy for contraction.

3. Regulates Contraction Speed: Different myosin heavy chain isoforms (α and β) control contraction velocity.

4. Maintains Heart Efficiency: Balances energy use and force production to support continuous heart function.

Structural Components:

• Myosin Heavy Chains (MHCs):

  • Contain the motor domain responsible for ATP binding and actin interaction.

  • Exist in two main isoforms:

    • α-Cardiac Myosin Heavy Chain (MYH6): Fast contraction, higher ATPase activity.

    • β-Cardiac Myosin Heavy Chain (MYH7): Slower contraction, more energy-efficient.

• Myosin Light Chains (MLCs):

  • Stabilize the myosin head and regulate activity.

  • Include essential light chains (ELCs) and regulatory light chains (RLCs).

Cardiac Myosin vs. Other Myosin Types:

Clinical Relevance of Cardiac Myosin:

• Cardiomyopathies:

  • Mutations in MYH7 are linked to hypertrophic (HCM) and dilated (DCM) cardiomyopathies, which affect heart function.

• Target for Heart Failure Drugs:

  • Myosin activators like Omecamtiv Mecarbil enhance contraction in heart failure patients.

  • Myosin inhibitors like Mavacamten are used to treat HCM by reducing excessive contractility.

• Regenerative Medicine:

  • Research is exploring how modifying myosin expression can aid in heart repair and recovery.