title: PDZ domain suppression of an ER retention signal in NMDA receptor NR1 splice variants.
abstract: The NMDA receptor NR1 subunit has four splice variants that differ in their C-terminal, cytoplasmic domain. We investigated the contribution of the C-terminal cassettes, C0, C1, C2, and C2', to trafficking of NR1 in heterologous cells and neurons. We identified an ER retention signal (RRR) in the C1 cassette of NR1, which is similar to the RXR motif in ATP-sensitive K(+) channels (Zerangue et al., 1999). We found that surface expression of NR1-3, which contains C1, is due to a site on the C2' cassette, which includes the terminal 4 amino acid PDZ-interacting domain. This site suppresses ER retention of the C1 cassette and leads to surface expression. These findings suggest a role for PDZ proteins in facilitating the transition of receptors from an intracellular pool to the surface of the neuron.
authors.affiliation: Laboratory of Neurochemistry, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA. standley@nidcd.nih.gov
authors.forename: S
authors.initials: S
authors.lastname: Standley
authors.forename: K W
authors.initials: KW
authors.lastname: Roche
authors.forename: J
authors.initials: J
authors.lastname: McCallum
authors.forename: N
authors.initials: N
authors.lastname: Sans
authors.forename: R J
authors.initials: RJ
authors.lastname: Wenthold
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D020816:Amino Acid Motifs / Q000235:genetics; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: C409466:NR1 NMDA receptor; C120997:NR2A NMDA receptor; C121001:NR2B NMDA receptor; D009419:Nerve Tissue Proteins; D016194:Receptors, N-Methyl-D-Aspartate; C033652:postsynaptic density proteins