Fig. 4: TARP PDZ interactions accumulate receptors at synaptic sites.
a Strategy for fluorescent labelling of surface AMPARs on rescue of knockout neurons using streptavidin labelling of biotinylated AMPARs (left), including schematic of AMPAR-TARP-tandem configuration (right). ER-localised BirA biotinylates the acceptor peptide (AP) on the receptor N-terminus. Example image (bottom) of surface AMPARs (red) in Cre-transduced (green) slices after co-rescue with tdTomato cell marker (blue). Similar results were obtained in 24 cells across four conditions and three preparations, presented across this figure, with additional representative images in Supplementary Figure 6. b GluA1_γ8 receptors accumulate in spines along the dendrite, while TARP PDZ mutation causes redistribution of receptors to the dendritic surface (see c for details). c Line profiles (left) of AMPAR fluorescence across spine and dendrite demonstrate enrichment of PDZ-containing receptors in spines. Quantification of receptor distribution (right) shows accumulation of GluA1_γ8 but not GluA1_γ8 ΔPDZ in spines. Box indicates 25–75%, whiskers represent max to min, with median represented as a centre line. (GluA1_γ8: 2.67 (1.73, 3.53) (median, (25%, 75%), n = 34 spines over seven cells (four slices per condition, two preparations); GluA1_γ8 ΔPDZ: 0.86 (0.67, 1.15), n = 25 spines over five cells; p < 0.0001). d NTD deletion of GluA1 (GluA1 ΔNTD) did not prevent AMPAR accumulation in dendritic spines as seen by surface receptor imaging (see e for details). e Line profiles (left), and spine enrichment quantification (right) demonstrate spin localisation of GluA1 ΔNTD (GluA1: 1.67 (1.34, 2.48), n = 25 spines over five cells (three slices per condition, one preparation); GluA1 ΔNTD: 1.63 (0.96, 2.52), n = 35 spines over seven cells; p < 0.52). Statistical significance was analysed using a Mann–Whitney test, *** indicates p < 0.001 and ns specifies no significance. Source data are provided as a source data file.
