FIGURE 22-24 PSD95 and gephyrin are scaffolding proteins for excitatory and inhibitory postsynaptic compartments, respectively. (a) The PDZ-containing protein PSD95 is part of the postsynaptic density at excitatory synapses and associates with glutamate receptors and with the actin cytoskeleton. The scaffolding protein gephyrin plays an analogous role at inhibitory synapses, where it associates with GABA receptors and with the microtubule and actin cytoskeletal networks. (b) PSD95 and gephyrin can be used to mark excitatory and inhibitory synapses, respectively. Shown in green are the PSD95-containing excitatory synapses and, in red, the gephyrin-containing inhibitory synapses that form on a single mouse cortical neuron in culture.

[Part (b) republished with permission of Elsevier, from Gross, G. et al., “Recombinant probes for visualizing endogenous synaptic proteins in living neurons,” Neuron, 2013, 78(6):971–85; permission conveyed through Copyright Clearance Center, Inc.]