Molecular determinants of NMDA receptor internalization
Katherine W. Roche1, Steve Standley1, Jennifer McCallum1, C. Dune Ly1, Michael D. Ehlers2
& Robert J. Wenthold1
1
Laboratory of Neurochemistry, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Building 36, Room 5B25, Bethesda, Maryland 20892, USA
2
Department of Neurobiology, Duke University Medical Center, Box 3209, Durham, North Carolina 27710, USA
Although synaptic AMPA receptors have been shown to rapidly internalize, synaptic NMDA receptors are reported to be static. It is not certain whether NMDA receptor stability at synaptic sites is an inherent property of the receptor, or is due to stabilization by scaffolding proteins. In this study, we demonstrate that NMDA receptors are internalized in both heterologous cells and neurons, and we define an internalization motif, YEKL, on the distal C-terminus of NR2B. In addition, we show that the synaptic protein PSD-95 inhibits NR2B-mediated internalization, and that deletion of the PDZ-binding domain of NR2B increases internalization in neurons. This suggests an involvement for PSD-95 in NMDA receptor regulation and an explanation for NMDA receptor stability at synaptic sites.
