Drug targets that fit the receptor-ligand model include

• A. DNA
• B. Enzymes, transporter proteins, structural proteins, and other cellular constituents
• C. Lipids
• D. Water channels

Answer: (B)

The main idea is that many drug effects come from binding to specific protein targets that can recognize and respond to ligands. These targets include enzymes, transporter proteins, structural proteins, and other cellular constituents, because each of these provides defined binding sites where a drug can attach and modulate activity or signaling. DNA can be targeted by drugs in ways that don’t involve the classic receptor-ligand response, and lipids or water channels aren’t typical receptor-like binding partners for producing the classic receptor-mediated effects. So, the best fit for the receptor-ligand model is enzymes, transporter proteins, structural proteins, and other cellular constituents.