PDZ domain, also called DHR (Dlg homologous region) or GLGF (after a conserved sequence motif). Many PDZ domains bind C-terminal polypeptides, though binding to internal (non-C-terminal) polypeptides and even to lipids has been demonstrated. Heterodimerization through PDZ-PDZ domain interactions adds to the domain's versatility, and PDZ domain-mediated interactions may be modulated dynamically through target phosphorylation. Some PDZ domains play a role in scaffolding supramolecular complexes. PDZ domains are found in diverse signaling proteins in bacteria, archebacteria, and eurkayotes. This CD contains two distinct structural subgroups with either a N- or C-terminal beta-strand forming the peptide-binding groove base. The circular permutation placing the strand on the N-terminus appears to be found in Eumetazoa only, while the C-terminal variant is found in all three kingdoms of life, and seems to co-occur with protease domains. PDZ domains have been named after PSD95(post synaptic density protein), DlgA (Drosophila disc large tumor suppressor), and ZO1, a mammalian tight junction protein.