This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
Which one of the following is not an NMDA receptor? 
Select and explain. 
A. Kappa, B. Kainate, C. AMPA, D. Glutamate
A: Kappa
Answer: A: Kappa 
Explanation: Ans: A (Kappa) Ref: Basic & Clinical Pharmacology, Katzung 12th ed p.367 Explanation: Kappa is an opioid receptor whereas the others are NMDA receptors.