M band

Definition

Target type: cellularcomponent

The midline of aligned thick filaments in a sarcomere; location of specific proteins that link thick filaments. Depending on muscle type the M band consists of different numbers of M lines. [GOC:mtg_muscle, ISBN:0198506732, ISBN:0815316194]

The M band is a dense, electron-dense structure located in the center of the sarcomere, the functional unit of striated muscle. It is a critical component of the muscle structure, playing a crucial role in the alignment and stability of thick filaments (myosin). Here's a detailed description of the cellular components of the M band:

**1. Myomesin:** This protein acts as a scaffold, forming the core of the M band. It binds to the myosin thick filaments, holding them in their proper position within the sarcomere. Myomesin also interacts with other M band proteins, contributing to the overall structural integrity.

**2. M-protein:** Another key component, M-protein is involved in the organization of the myosin thick filaments within the M band. It interacts with myosin, myomesin, and other proteins, ensuring the precise arrangement of the thick filaments.

**3. Obscurin:** This large protein interacts with myosin and titin, two major muscle proteins. Obscurin helps to connect the M band to the Z-disk, the structure at the ends of the sarcomere. It also plays a role in signaling pathways within the muscle fiber.

**4. Myosin Binding Protein C (MyBP-C):** While primarily associated with the thick filament, MyBP-C also has a presence in the M band. It contributes to the regulation of myosin activity and may help to connect the M band to the thick filament.

**5. Other Proteins:** The M band also contains a variety of other proteins, including:
- **C-protein:** Helps to regulate myosin activity.
- **Projectin:** Plays a role in muscle elasticity and force generation.
- **Skeletal Muscle LIM Protein (SLIM):** Involved in sarcomere assembly and stability.

**Overall, the M band is a complex and dynamic structure that plays a crucial role in muscle function. Its components are essential for the precise alignment and stability of the thick filaments, contributing to the overall organization and contractile ability of the sarcomere.**'
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Proteins (2)

Compounds (4)