Structures of PDZ, PDZ-like, PDZ-PDZ dimer, and tandem PDZ domains. (A) Ribbon diagram of Dvl-1 PDZ (PDB code: 2KAW). (B) HtrA2 PDZ (PDB code: 1LCY). (C) ZO-1 PDZ2 (PDB code:2RCZ). (D) GRIP-1 PDZ1+2 (PDB code: 2QT5). The binding site of each PDZ domain is shown by a yellow oval. The structures were generated using the Pymol software.