Sonication dissociates the synaptic cleft and allows purification of postsynaptic densities with associated postsynaptic membrane

In the synaptic junction, pre-and post compartments are anchored to each other through trans-synaptic bridges spanning the synaptic cleft. Here we demonstrate that mild mechanical disturbance through sonication dissociates the synaptic cleft, and releases PSDs adjoined to the postsynaptic membrane, but devoid of presynaptic elements. It is the first time, to our knowledge, that dissection of the synaptic cleft has been achieved without the use of chemical/enzymatic treatments. This observation suggests that some of the protein-protein interactions involved in the anchoring of pre- and postsynaptic compartments are relatively weak non-covalent associations. We describe a method for the further fractionation of PSDs with the associated postsynaptic membrane. This PSD preparation provides a valuable tool for studies of postsynaptic membrane components, such as glutamatergic receptors, in an environment closer to their native state.