Question

Hormones those bind to intracellular receptors
(A). Androgens
(B). Estrogen
(C). Progestine
(D). Insulin
Choose the correct answer from the options given below:

• A. (A), (B) and (C) only.
• B. (A), (B) and (D) only.
• C. (A), (B), (C) and (D).
• D. (B), (C) and (D) only.

Hint:

To easily identify receptor locations:
- Steroid hormones (derived from cholesterol) and Thyroid hormones (T3/T4) are lipophilic and bind to intracellular receptors.
- Peptide/Protein hormones (like Insulin and Glucagon) and Catecholamines are hydrophilic and bind to cell-surface receptors.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Hormones are chemical messengers classified based on their solubility: hydrophilic (water-soluble) and lipophilic (lipid-soluble).
This chemical nature dictates whether their receptors are located on the cell surface or inside the cell (intracellularly).

Step 2: Detailed Explanation:
Let us evaluate each of the listed hormones:
- (A) Androgens, (B) Estrogen, and (C) Progestine: These are steroid hormones derived from cholesterol.
Due to their lipophilic nature, they easily diffuse across the hydrophobic lipid bilayer of the target cell's plasma membrane.
Once inside the cell, they bind to specific intracellular receptors located in the cytoplasm or the nucleus.
The ligand-receptor complex then acts as a ligand-activated transcription factor, binding to hormone response elements (HREs) on the DNA to regulate gene expression.
- (D) Insulin: This is a hydrophilic peptide hormone.
Because it cannot cross the plasma membrane, it binds to a specific cell-surface receptor—the insulin receptor, which is a transmembrane receptor tyrosine kinase.
This triggers an intracellular phosphorylation cascade without the hormone entering the cell.
Therefore, only the steroid hormones—Androgens, Estrogen, and Progestine—bind to intracellular receptors.

Step 3: Final Answer:
The correct combination is (A), (B), and (C) only, corresponding to option (A).