title: Selective binding of synapse-associated protein 97 to GluR-A alpha-amino-5-hydroxy-3-methyl-4-isoxazole propionate receptor subunit is determined by a novel sequence motif.
abstract: A family of four closely related PDZ domain-containing membrane-associated guanylate kinase homologues (MAGUKs) is involved in the regulation of the amount and functional state of ionotropic glutamate receptors in excitatory synapses. To understand the mechanisms that determine the specificity of these interactions, we examined the structural basis of the highly selective association between the ionotropic GluR subunit GluR-A and synapse-associated protein 97 (SAP97). The C terminus of GluR-A bound to the PDZ domains of SAP97, but not to those of three related MAGUKs, PSD-93, PSD-95, and SAP102. Experiments with single PDZ domains indicated that the strongest contribution was by the second PDZ domain. Unexpectedly, mutation analysis of the GluR-A C terminus revealed that a tripeptide sequence SSG at position -9 to -11 plays an essential role in this binding, in addition to a C-terminal type I PDZ binding motif (leucine at C terminus and threonine at the -2 position). Analysis of the in vitro MAGUK-binding properties of a GluR-D mutant with a one-residue deletion at the C terminus provides further support for the view that an SSG sequence located N-terminally from a type I PDZ binding motif can mediate selective binding to SAP97 and suggest the existence of a novel variation of the PDZ domain-peptide interaction.
authors.affiliation: Department of Biosciences, Division of Biochemistry, University of Helsinki, Helsinki FIN-00014, Finland.
authors.forename: Chunlin
authors.initials: C
authors.lastname: Cai
authors.forename: Sarah K
authors.initials: SK
authors.lastname: Coleman
authors.forename: Katri
authors.initials: K
authors.lastname: Niemi
authors.forename: Kari
authors.initials: K
authors.lastname: Keinänen
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D002531:Cerebellum / Q000378:metabolism*; D003001:Cloning, Molecular; D017931:DNA Primers; D000074288:Discs Large Homolog 1 Protein; D004926:Escherichia coli / Q000235:genetics; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D051528:Guanylate Kinases; D006801:Humans; D007668:Kidney; D008297:Male; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D021122:Protein Subunits; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D025521:Tumor Suppressor Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D017931:DNA Primers; D000074288:Discs Large Homolog 1 Protein; D005982:Glutathione Transferase; D051528:Guanylate Kinases; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D021122:Protein Subunits; D018091:Receptors, AMPA; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D025521:Tumor Suppressor Proteins; C513314:DLG1 protein, human; C501119:Dlg1 protein, rat; C496468:DLG2 protein, human