Which one of the following is a contractile protein

Options

A. Collagen
B. Elastin
C. Tropomyosin
D. Keratin

Answer

To determine which of the given proteins is a contractile protein, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Contractile Proteins**:
- Contractile proteins are proteins that facilitate the contraction of muscle fibers. They are essential for muscle movement and are involved in the sliding mechanism of muscle contraction.

2. **Identify the Options**:
- The options provided are:
- Collagen
- Elastin
- Tropomyosin
- Keratin

3. **Analyze Each Option**:
- **Collagen**: This is primarily a structural protein that provides strength and support to various tissues. It is not involved in muscle contraction.
- **Elastin**: This protein is found in connective tissues and allows tissues to resume their shape after stretching or contracting. It is not a contractile protein.
- **Tropomyosin**: This is a contractile protein that works alongside actin and myosin in muscle contraction. It regulates the contraction process in both muscle and non-muscle cells.
- **Keratin**: This is a structural protein found in hair, nails, and the outer layer of skin. It is not involved in muscle contraction.

4. **Select the Correct Answer**:
- Based on the analysis, the correct answer is **Tropomyosin**, as it is the only protein among the options that functions as a contractile protein.

### Final Answer:
The correct answer is **Tropomyosin**.

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