Myosin V

Definition

Myosin V is a motor protein that plays a crucial role in cellular transport by interacting with actin filaments, facilitating the movement of cargo within cells. This protein is known for its ability to move along actin filaments in a process that requires ATP, making it essential for various cellular functions such as organelle transport, vesicle movement, and cell division.

5 Must Know Facts For Your Next Test

1. Myosin V is characterized by its long neck and two motor domains, which allow it to take larger steps along actin filaments compared to other myosins.
2. This motor protein is crucial for the transport of organelles such as melanosomes in melanocytes and synaptic vesicles in neurons.
3. Myosin V operates through a 'hand-over-hand' mechanism, where each head alternately binds and releases from the actin filament, enabling efficient movement.
4. The action of myosin V is regulated by binding to specific cargo as well as by phosphorylation states, influencing its activity and transport efficiency.
5. Mutations in the gene encoding myosin V can lead to disorders such as Griscelli syndrome, which affects pigmentation and immune responses due to impaired organelle transport.

Review Questions

• How does myosin V contribute to intracellular transport, and what is its mechanism of action?
  • Myosin V contributes to intracellular transport by moving along actin filaments to carry various types of cargo, including organelles and vesicles. It operates using a unique 'hand-over-hand' mechanism where its two motor domains alternately bind to the actin filament, allowing it to take larger steps. This efficient movement is powered by ATP, making myosin V essential for processes like organelle positioning and vesicle trafficking within the cell.
• Discuss the structural features of myosin V that facilitate its function in transporting cellular cargo.
  • Myosin V has distinct structural features that enhance its ability to transport cargo effectively. It possesses a long neck region, which increases the distance between its motor domains, allowing it to take larger strides on actin filaments. Additionally, the two motor domains enable it to perform coordinated movements while ensuring stability during transport. These structural characteristics optimize myosin V's functionality as a motor protein involved in intracellular transport processes.
• Evaluate the implications of myosin V mutations on cellular function and how they relate to diseases such as Griscelli syndrome.
  • Mutations in myosin V can severely impact cellular function by disrupting its ability to transport organelles effectively. In diseases like Griscelli syndrome, these mutations lead to impaired transport of melanosomes, resulting in reduced pigmentation and immune deficiencies. Evaluating the role of myosin V mutations highlights how critical this motor protein is for normal cellular activities and showcases the broader implications for understanding transport mechanisms and associated disorders.

Related terms

Actin Filaments: Thin protein filaments that are part of the cytoskeleton, providing structural support and playing a vital role in cellular movement and shape.

ATP (Adenosine Triphosphate): The primary energy carrier in all living organisms, ATP provides the energy necessary for myosin V to perform its function in moving along actin filaments.

Motor Proteins: Proteins that convert chemical energy into mechanical work, facilitating movement along cytoskeletal filaments and transporting cellular cargo.