Distribution of Densin label within the PSD.

Distances of gold particles from the postsynaptic membrane were measured in three experiments. Histograms show the percentage of label in consecutive laminar layers (10 nm bins). Under basal (control) conditions 90% of densin label is confined within the PSD core (40 nm from the postsynaptic membrane, marked by a dashed line on histograms). Following depolarization with high K+ (90 mM for 2 min) a slight shift of label towards the PSD pallium (40–120 nm from the postsynaptic membrane) was observed, with 77% of label remaining within the PSD core.