Interaction partners of PSD-93 studied by X-ray crystallography and fluorescence polarization spectroscopy

The structure of PSD-93 PDZ1 with a C-terminal GTSI extension to mimic the C-terminal tail of GluD2 shows flexibility in the binding cavity, resulting in variations in GTSI binding. Combined with the very low binding affinity of a GluD2 C-terminally derived peptide to PSD-93 PDZ1, PDZ2 and PDZ1-2, it raises doubts about the role of PSD-93 as a direct intracellular GluD2 receptor interaction partner.