Eag1 voltage-gated potassium channels enter and leave synapses by lateral diffusion.

(A) Left, histogram showing the changes of D_i values over time for Eag1 channels in hippocampal neuronal cultures. Right, consecutive frames of a representative recording showing diffusion of Eag1 channels inside a presynaptic terminal (Panel 1) and between different presynaptic terminals (Panel 2 and 3; scale bar: 1µm). (B) D_i values were fitted to MSD plots generated from either extrasynaptic or synaptic trajectories composed of at least 10 consecutive frames. After binning with a step size of 0.025 µm²/s the number of trajectories was plotted over D_i values. Insets, examples of synaptic and extrasynaptic trajectories (scale bar: 200 nm). (C) Median diffusion (±25–75% interquartile range) values for Eag1 channels in extrasynaptic and synaptic trajectories based on data from (B). (D) MSD plots versus time for Eag1 channels inside a synapse (upper graph, consecutive panels from a1 to a3) and outside a synapse (lower graph, consecutive panels from a4 to a6; scale bar: 1µm).