Levels of proteins involved in secretion depend on synapse location. (A) Example images of hippocampal network cultures stained for dendrite marker MAP and presynaptic proteins. Bars, 20 µm. (B) Cumulative histograms of the synaptic intensity of proteins involved in vesicle release. Synapses were grouped based on their distance from the postsynaptic soma. All intensities were normalized to the largest value per cell. P/D is the ratio of proximal (<50 µm) over distal (last 50 µm), and p-value is the significance of the P/D ratio. N represents the number of independent experiments. (C) Surface area of vGAT and VAMP puncta. BSN, Bassoon; M18, Munc18; Syn, Synapsin; Syt, Synaptotagmin; Syx, Syntaxin.