Why can conformational changes in one subunit of a protein complex affect other subunits?

• A. Subunits are linked through their backbone, allowing changes to propagate.
• B. Subunits are isolated, preventing any interaction.
• C. Subunits are covalently linked, ensuring changes are transmitted.
• D. Subunits are closely associated, allowing changes to propagate through non-covalent interactions.

Answer: (D)