Interaction between the C terminus of NMDA receptor subunits and multiple members of the PSD-95 family of membrane-associated guanylate kinases

Abstract

Selective concentration and anchoring of ionotropic receptors at the synapse is essential for neuronal signaling. Little is known about the molecules that mediate receptor clustering in the CNS. With use of the yeast two-hybrid system to screen a rat brain cDNA library and by in vitro binding assays, we have identified an interaction between NMDA receptor subunits 2A and 2B (NR2A and NR2B) and three distinct members of the PSD-95/SAP90 family of membrane-associated putative guanylate kinases. The interaction is mediated by binding of the C terminus of the NMDA receptor subunits to the first two PDZ (also known as GLGF or DHR) domains of PSD-95/SAP90, an abundant synaptic protein associated with the membrane cytoskeleton. PSD-95 is also known to bind and cluster Shaker-type voltage-gated K+ channels. Similarities between the C-termini of NR2 subunits and K+ channels suggest a common C-terminal binding motif for PDZ domains. These data suggest that PDZ domains can function as modules for protein-protein interactions. Members of the PSD-95 family might serve to anchor NMDA receptors to the submembrane cytoskeleton and aid in the assembly of signal transduction complexes at postsynaptic sites.

Nicotinic α7 receptors: Synaptic options and downstream signaling in neurons

“…The PDZ domain is a module of about 90 amino acids designed to bind to other proteins (Sheng and Sala, 2001). One of the first PDZ proteins discovered, PSD-95, was shown to bind directly to the C-terminus of NR2 subunits in NMDA receptors and induced clustering of the receptors in cotransfected cells (Kornau et al, 1995;Niethammer et al, 1996). Whether PSD-95 is responsible for positioning native NMDA receptors at synapses in vivo is an open question, but it is clear that the protein can function as an organizing scaffold that tethers other components to the receptors (Tomita et al, 2001;Hung and Sheng, 2002).…”

In vivo blockade of N-methyl-d-aspartate receptors induces rapid trafficking of NR2B subunits away from synapses and out of spines and terminals in adult cortex

“…How might this subunit-specific trafficking be achieved? The anchoring protein, PSD-95, binds to the PDZ-binding domain that is common to all NR2 subunits (Niethammer et al, 1996;Sheng, 2001). One possible mechanism for trafficking the NR2A-and NR2B-containing NMDA receptors in opposite directions is that PSD-95 responds to NMDA receptor blockade with intramolecular structural changes, leading to an increased affinity of PSD-95 for the NR2A subunits and decreased affinity for the NR2B subunits.…”

“…Among the NMDA receptor subunits, the NR1 is necessary for NMDA receptor function, but the NR2 subunits may be relatively more central in determining NMDA receptor localization (Mori et al, 1998;Steigerwald et al, 2000;Mohrmann et al, 2002) because their C-termini are longer and permit interaction with postsynaptic density (PSD) scaffolding proteins, such as PSD-95 (Niethammer et al, 1996;Bassand et al, 1999;Sheng and Pak, 2000). Among the NR2 subunits, the NR2A and NR2B subtypes are the most prevalent in the cerebral cortex (Watanabe et al, 1992), and of the two, the NR2B subunits are shown to be particularly influential in learning and memory (Tang et al, 1999;Tang and Schuman, 2002) as they prolong NMDA receptor currents, thus allowing greater Ca influx (Mori and Mishina, 1995;Dingledine et al, 1999).…”

The C-terminus of the HTLV-1 Tax oncoprotein mediates interaction with the PDZ domain of cellular proteins

“…The ®rst two PDZ domains of PSD-95 have been shown to interact with the cytoplasmic tails of subunits of the NMDA glutamate receptor and of Shaker-type K + channels (Kim et al, 1995;Kornau et al, 1995;Niethammer et al, 1996). It has also been shown that the PDZ domains of FAP-1 mediate interaction with the C-terminus of Fas (Sato et al, 1995).…”