Using electron microscopy replica immunolabelling, we have provided evidence for distinct nanoscale arrangements of presynaptic release sites and voltage-gated Ca2+ channels in two distinct cerebellar synapses. We have also shown that the distinct nanoscale distributions of Ca2+ channels around docked vesicles are responsible for distinct release probabilities (Rebola et al., 2019, Neuron).
We have demonstrated large functional diversity of synapses made by hippocampal CA1 pyramidal cells and fast-spiking GABAergic interneurons. The large variability in EPSC amplitude is the consequence of variable numbers of functional release sites between the connected nerve cells. Molecular analysis of the functionally characterized synapses has revealed that synapses with the same number of release sites contain variable amounts of Munc13-1 molecules; a key vesicle docking/priming factor. These Munc13-1 molecules are arranged in nanoclusters within the active zones, the number of which equals that of functional release sites. These nanoclusters have variable sizes and contain different numbers of Munc13-1 molecules (Karlocai et al., 2021, eLife).
We have developed a quantitative, high-resolution, multiplexed immunolocalization method that allows the proteomic analysis of functionally characterized single synapses with a resolution of about 40 nm (Holderith et al., 2020, Cell Rep).
Using pharmacological, physiological and computer modelling approaches, we have demonstrated that the unreliability of a given hippocampal synapse is the consequence of synaptic vesicles that are not capable of fusing with the plasma membrane (fusion incompetent) rather than the low fusion probability of fusion-competent vesicles (Aldahabi et al., 2024, PNAS).
