title: Interaction between SAP97 and PSD-95, two Maguk proteins involved in synaptic trafficking of AMPA receptors.
abstract: Synapse-associated protein 97 (SAP97) and postsynaptic density 95 (PSD-95) are closely related membrane-associated guanylate kinase homologs (Maguks) implicated in the synaptic targeting and anchoring of alpha-amino-5-methyl-3-hydroxy-4-isoxazolepropionic acid (AMPA)-selective glutamate receptors. Prompted by accumulating evidence for an oligomeric nature of Maguks, we examined the potential of SAP97 and PSD-95 to form heteromeric complexes. SAP97 and PSD-95 coimmunoprecipitated from rat brain detergent extracts and subsequent glutathione S-transferase pull-down and immunoprecipitation experiments showed that the interaction is mediated by binding of the N-terminal segment of SAP97 (SAP97(NTD)) to the Src homology 3 domain of PSD-95 (PSD-95(SH3)). In cultured hippocampal neurons, expression of green fluorescent protein-tagged PSD-95 triggered accumulation of SAP97 in synaptic spines, which was totally inhibited by coexpression of PSD-95(SH3). Furthermore, overexpression of green fluorescent protein-PSD-95 induced dendritic clustering of GluR-A subunit-containing AMPA receptors, which was strongly inhibited by cotransfection with SAP97(NTD) and PSD-95(SH3) constructs. Our results demonstrated a direct interaction between SAP97 and PSD-95 and suggested that this association may play a functional role in the trafficking and clustering of AMPA receptors.
authors.affiliation: Department of Biological and Environmental Sciences, University of Helsinki, Finland.
authors.forename: Chunlin
authors.initials: C
authors.lastname: Cai
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Claudio
authors.initials: C
authors.lastname: Rivera
authors.forename: Kari
authors.initials: K
authors.lastname: Keinänen
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000502:physiology*; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D002478:Cells, Cultured; D000074288:Discs Large Homolog 1 Protein; D000076122:Disks Large Homolog 4 Protein; D051528:Guanylate Kinases; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology*; D051379:Mice; D021381:Protein Transport; D051381:Rats; D018091:Receptors, AMPA / Q000378:metabolism*; D017470:Receptors, Glutamate / Q000378:metabolism; D013569:Synapses / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C513314:DLG1 protein, human; D000074288:Discs Large Homolog 1 Protein; D000076122:Disks Large Homolog 4 Protein; C000614189:Dlg1 protein, mouse; C501119:Dlg1 protein, rat; C501447:Dlg4 protein, mouse; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; D051528:Guanylate Kinases