The globular head of a heavy meroyosin part of mermyosin has :

Options

A. Actin binding sites
B. ATP binding sites
C. ATPase enzyme activity
D. All of the above

Answer

To solve the question regarding the globular head of heavy meromyosin, we can break it down into the following steps:

### Step 1: Understand the Structure of Myosin
- Myosin is a contractile protein that forms thick filaments in muscle fibers. It is composed of monomer units called meromyosin.

**Hint:** Myosin is made up of smaller units called meromyosin.

### Step 2: Identify the Components of Meromyosin
- Meromyosin consists of two parts: heavy meromyosin and light meromyosin. The heavy meromyosin includes the globular head and a short arm, while the light meromyosin forms the tail.

**Hint:** Meromyosin is divided into heavy and light parts.

### Step 3: Focus on the Heavy Meromyosin
- The heavy meromyosin contains the globular head, which is crucial for its function. This globular head has specific binding sites and enzymatic activity.

**Hint:** Heavy meromyosin is characterized by its globular head.

### Step 4: Identify the Functions of the Globular Head
- The globular head of heavy meromyosin has:
- A binding site for actin (the thin filament).
- A binding site for ATP (adenosine triphosphate).
- ATPase enzymatic activity, which is essential for muscle contraction.

**Hint:** The globular head is involved in binding and enzymatic reactions.

### Step 5: Conclusion
- Therefore, the correct answer to the question is that the globular head of heavy meromyosin has binding sites for actin and ATP, as well as ATPase activity.

**Final Answer:** The globular head of heavy meromyosin has binding sites for actin, ATP, and possesses ATPase activity. Thus, the correct option is "all of the above."