Crystal structures of a complexed and peptide-free membrane protein-binding domain: molecular basis of peptide recognition by PDZ.
Doyle, D.A., Lee, A., Lewis, J., Kim, E., Sheng, M., MacKinnon, R.(1996) Cell 85: 1067-1076
- PubMed: 8674113 
- DOI: https://doi.org/10.1016/s0092-8674(00)81307-0
- Primary Citation of Related Structures:  
1BE9, 1BFE - PubMed Abstract: 
Modular PDZ domains, found in many cell junction-associated proteins, mediate the clustering of membrane ion channels by binding to their C-terminus. The X-ray crystallographic structures of the third PDZ domain from the synaptic protein PSD-95 in complex with and in the absence of its peptide ligand have been determined at 1.8 angstroms and 2.3 angstroms resolution, respectively. The structures reveal that a four-residue C-terminal stretch (X-Thr/Ser-X-Val-COO(-)) engages the PDZ domain through antiparallel main chain interactions with a beta sheet of the domain. Recognition of the terminal carboxylate group of the peptide is conferred by a cradle of main chain amides provided by a Gly-Leu-Gly-Phe loop as well as by an arginine side chain. Specific side chain interactions and a prominent hydrophobic pocket explain the selective recognition of the C-terminal consensus sequence.
Organizational Affiliation: 
Laboratory of Molecular Neurobiology and Biophysics, The Rockefeller University, New York, NY 10021, USA.