A drug found to bind to the NMDA receptor might be a positive allosteric modulator if:
A) some of the receptors the drug binded to became activated while others were not.
B) the drug alone caused ions to flow through the NMDA receptor channel.
C) reduced ion flow through the NMDA receptor channel occurred when glutamate was bound to the receptor with the drug present.
D) greater ion flow through the NMDA receptor occurred when glutamate was bound to the receptor with the drug present.

Question

Quizplus · Accepted Answer

A positive allosteric modulator enhances the activity of the receptor when the primary ligand (in this case, glutamate) is bound. Therefore, greater ion flow through the NMDA receptor channel would indicate that the drug is a positive allosteric modulator. Option A is incorrect because binding to some receptors but not others does not define allosteric modulation. Option B is incorrect because the drug alone causing ion flow would indicate that it is an agonist rather than a modulator. Option C is incorrect because reduced ion flow when glutamate is bound would indicate that the drug is a negative allosteric modulator.

A Drug Found to Bind to the NMDA Receptor Might