Question

Which of the following is true for lipophilic hormones?

• A. Lipophilic hormones cross the plasma membrane
• B. Inside the target cell, the steroid hormone binds to a specific receptor protein in the cytoplasm or nucleus.
• C. Hormone-receptor complex enters the nucleus and binds to DNA, causing gene transcription.
• D. Protein synthesis is induced.

Answer 1

Answer: (A), (B), (C), (D)

Protein synthesis is induced.

Steroid hormones are lipid-soluble and thus readily diffuse through the plasma membrane of cells. They bind to receptor proteins in either the cytoplasm or nucleus. If the steroid binds to a receptor in the cytoplasm, the hormone-receptor complex moves into the nucleus. The hormone-receptor complex then binds to specific regions of the DNA, stimulating the production of messenger RNA (mRNA) and protein synthesis. Other steroids travel directly into the nucleus before encountering their receptor proteins. Whether the steroid finds its receptor in the nucleus or translocates with its receptor to the nucleus from the cytoplasm, the rest of the story is the same.