Vitamin D is a relatively small, lipid-soluble molecule that can behave as a hormone.Its receptor, therefore, most likely
A) is an ion channel receptor.
B) is a protein kinase receptor.
C) involves a G protein.
D) is located inside the cell.
E) does not exist, since the molecule can diffuse across the cell membrane.

Question

Quizplus · Accepted Answer

Since vitamin D is a lipid-soluble molecule that can behave as a hormone, its receptor is most likely located inside the cell. This is because lipid-soluble molecules can diffuse across the cell membrane and bind to intracellular receptors such as nuclear receptors, which are located inside the cell. This is in contrast to water-soluble hormones that bind to extracellular receptors on the cell surface. Therefore, choice D is the best answer.

Vitamin D Is a Relatively Small, Lipid-Soluble Molecule That Can