The hormone which acts through intracellular receptor protein is

Options

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

Answer

To determine which hormone acts through intracellular receptor proteins, we can analyze the options provided: growth hormone, prolactin, thyronine, and adenine.

### Step-by-Step Solution:

1. **Understanding Hormone Types**:
- Hormones can be classified based on their chemical nature into three main categories: peptide hormones, steroid hormones, and amino acid derivatives.
- Peptide hormones (like insulin, growth hormone, and prolactin) typically have receptors that are membrane-bound and do not enter the cell.
- Steroid hormones (like cortisol, estrogen, and progesterone) and thyroid hormones (like thyroxine) have receptors that are located inside the cell (intracellular receptors).

2. **Analyzing the Options**:
- **Growth Hormone**: This is a peptide hormone and has membrane-bound receptors.
- **Prolactin**: This is also a peptide hormone with membrane-bound receptors.
- **Thyronine (Thyroxine)**: This is a thyroid hormone, which is classified as an iodothyronine. Thyroid hormones have intracellular receptors.
- **Adenine**: This is not a hormone; it is a nucleobase and does not act through hormone receptors.

3. **Identifying the Correct Answer**:
- Among the options, the only hormone that acts through intracellular receptor proteins is **thyronine (thyroxine)**. This hormone binds to receptors located inside the cell, influencing gene expression.

### Conclusion:
The hormone which acts through intracellular receptor protein is **thyronine (thyroxine)**.

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