The hormone which acts through intracellular receptor protein is

Options

A. Growth hormone
B. Prolactin
C. Thyroxine
D. Adrenaline

Answer

To answer the question about which hormone acts through intracellular receptor proteins, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Receptor Proteins**:
- Receptor proteins are molecules that receive signals from hormones. They can be located either on the surface of the cell (extracellular receptors) or inside the cell (intracellular receptors).

2. **Identify Intracellular Receptor Proteins**:
- Intracellular receptor proteins are found within the cytoplasm or nucleus of the cell. They bind to hormones that can pass through the cell membrane.

3. **Know the Types of Hormones**:
- Hormones can be classified into two main categories based on their structure and the type of receptor they bind to:
- **Steroid Hormones**: These hormones are lipid-soluble and can easily cross cell membranes. They typically act through intracellular receptors.
- **Peptide Hormones**: These hormones are water-soluble and usually bind to extracellular receptors on the cell surface.

4. **Examples of Hormones Acting Through Intracellular Receptors**:
- The hormones that act through intracellular receptors include:
- **Steroid Hormones**: Such as cortisol, testosterone, and estrogen.
- **Thyroid Hormones**: Such as thyroxine (T4) and triiodothyronine (T3).

5. **Conclusion**:
- Among the hormones mentioned, the one that acts through intracellular receptor proteins is **thyroxine** (T4), which is a thyroid hormone.

### Final Answer:
The hormone which acts through intracellular receptor protein is **thyroxine**.

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