Figure 7.

M3 of NR1 and NR2B are necessary for the negating of the ER retention signals in M3 of NR2B and NR1. A, COS7 cells transfected with indicated combinations of NMDA receptor subunits were immunostained for surface GFP. Schematic drawings of membrane topology of NR1 (gray) and NR2B (black) subunits with replaced M3 for AchR α M4 (white) are shown. B, The percentages of surface-labeled transfected cells determined for each NR1/NR2 combination from >300 cells in three experiments are shown in mean ± SEM. C, Data represent mean ± SEM of surface (black) and total (white) fluorescence intensities per unit area of indicated combinations of subunits; n >45 cells in three experiments. **p < 0.001, unpaired t test.