Figure 4.

MAP1B-GRIP1 interaction in vivo in hippocampus. A, MAP1B colocalizes with GRIP1 in dendritic shafts of hippocampal pyramidal neurons. Scale bar, 10 μm. B, GRIP or GluR2 coimmunoprecipitation demonstrates a complex between MAP1B, GRIP, and GluR2 but not PSD95. C, Western blot of biotinylated proteins showing that NMDA or DHPG treatments induce AMPAR endocytosis. n = 3 experiments; *p < 0.05. Total AMPAR (Tot) and isolated biotin-labeled surface GluR2 protein (Surf) from NMDA- or DHPG-treated hippocampal lysates were analyzed by Western blot. D, GRIP coimmunoprecipitation showing that DHPG treatment is associated with increased binding of MAP1B to GRIP1. E, Quantitation of the MAP1B/GRIP1 ratio; NMDA n = 4, DHPG n = 6; *p < 0.05. F, Coimmunoprecipitation experiment demonstrates that rapamycin (Rap.) pretreatment blocks the DHPG-dependent increase in GRIP–MAP1B association. C, Control; N, NMDA; D, DHPG.