title: PSD-95 is a negative regulator of the tyrosine kinase Src in the NMDA receptor complex.
abstract: The tyrosine kinase Src upregulates the activity of the N-methyl-D-aspartate subtype of glutamate receptor (NMDAR) and tyrosine phosphorylation of this receptor is critical for induction of NMDAR-dependent plasticity of synaptic transmission. A binding partner for Src within the NMDAR complex is the protein PSD-95. Here we demonstrate an interaction of PSD-95 with Src that does not require the well-characterized domains of PSD-95. Rather, we show binding to Src through a 12-amino-acid sequence in the N-terminal region of PSD-95, a region not previously known to participate in protein-protein interactions. This region interacts directly with the Src SH2 domain. Contrary to typical SH2 domain binding, the PSD-95-Src SH2 domain interaction is phosphotyrosine-independent. Binding of the Src-interacting region of PSD-95 inhibits Src kinase activity and reduces NMDAR phosphorylation. Intracellularly administering a peptide matching the Src SH2 domain-interacting region of PSD-95 depresses NMDAR currents in cultured neurons and inhibits induction of long-term potentiation in hippocampus. Thus, the PSD-95-Src SH2 domain interaction suppresses Src-mediated NMDAR upregulation, a finding that may be of broad importance for synaptic transmission and plasticity.
authors.affiliation: Division of Neurology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Lorraine V
authors.initials: LV
authors.lastname: Kalia
authors.forename: Graham M
authors.initials: GM
authors.lastname: Pitcher
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Pelkey
authors.forename: Michael W
authors.initials: MW
authors.lastname: Salter
mesh_terms: D000818:Animals; D002460:Cell Line; D000076122:Disks Large Homolog 4 Protein; D015536:Down-Regulation / Q000502:physiology; D051528:Guanylate Kinases; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism*; D013569:Synapses / Q000235:genetics / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology*; D018909:src Homology Domains / Q000235:genetics; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D016194:Receptors, N-Methyl-D-Aspartate; D019061:src-Family Kinases; D051528:Guanylate Kinases