Describe the intracellular receptor characteristic.

• A. It is always located on the cell surface.
• B. It mediates signals without entering the nucleus.
• C. It cannot bind DNA.
• D. It binds a ligand and can bind DNA, unlike membrane receptors.

Answer: (D)

Intracellular receptors are proteins located inside the cell (cytoplasm or nucleus) that bind ligands capable of crossing the cell membrane, such as steroid hormones. When a ligand binds, the receptor commonly changes shape and then interacts with DNA to regulate transcription, acting as a transcription factor. This direct ability to bind DNA and influence gene expression is what distinguishes intracellular receptors from membrane receptors, which stay on the cell surface and typically signal through cascades without directly binding DNA. The other statements don’t fit because being on the cell surface is not always true for intracellular receptors, they often influence gene expression by entering the nucleus, and they can bind DNA, which some membrane receptors do not.