3D structure of a bound PDZ domain. The PDZ domain folds into a structure consisting of six β strands and two α helices. Canonical interactions occur through C-terminal target side chain interactions and the hydrophobic domain binding pocket formed between domain strand β2 and helix α2. The ten core domain binding sites are highlighted in blue and the bound peptide (RRETQV) is in orange. PDB:2OQS (NMR first model).