PMID:15317856

Citation	Abe, M, Fukaya, M, Yagi, T, Mishina, M, Watanabe, M and Sakimura, K (2004) NMDA receptor GluRepsilon/NR2 subunits are essential for postsynaptic localization and protein stability of GluRzeta1/NR1 subunit. J. Neurosci. 24:7292-304
Abstract	In NMDA receptors, GluRepsilon/NR2 subunits strictly require the GluRzeta1/NR1 subunit to exit from endoplasmic reticulum (ER) to the cell surface in vitro and to the postsynapse in vivo, whereas C terminus-dependent self-surface delivery has been demonstrated for the GluRzeta1 subunit in vitro. To test whether this leads to C terminus-dependent self-postsynaptic expression in neurons in vivo, we investigated the GluRzeta1 subunit in cerebellar granule cells lacking two major GluRepsilon subunits, GluRepsilon1/NR2A and GluRepsilon3/NR2C. In the mutant cerebellum, synaptic labeling for the GluRzeta1 subunit containing the C2 (GluRzeta1-C2) or C2' (GluRzeta1-C2') cassette was reduced at mossy fiber-granule cell synapses to the extrasynaptic level. The loss was not accompanied by decreased transcription and translation levels, increased extrasynaptic labeling, or ER accumulation. Quantitative immunoblot revealed substantial reductions in the mutant cerebellum of GluRzeta1-C2 and GluRzeta1-C2'. The most severe deficit was observed in the postsynaptic density (PSD) fraction: mutant levels relative to the wild-type level were 12.3 +/- 3.3% for GluRzeta1-C2 and 17.0 +/- 4.6% for GluRzeta1-C2'. The GluRzeta1 subunit carrying the C1 cassette (GluRzeta1-C1) was, although low in cerebellar content, also reduced to 12.7 +/- 3.5% in the mutant PSD fraction. Considering a trace amount of other GluRepsilon subunits in the mutant cerebellum, the severe reductions thus represent that the GluRzeta1 subunit, by itself, is virtually unable to accumulate at postsynaptic sites, regardless of C-terminal forms. By protein turnover analysis, the degradation of the GluRzeta1 subunit was accelerated in the mutant cerebellum, being particularly rapid for that carrying the C2 cassette. Therefore, accompanying expression of GluRepsilon subunits is essential for postsynaptic localization and protein stability of the GluRzeta1 subunit.
Links	PubMed Online version:10.1523/JNEUROSCI.1261-04.2004
Keywords	Animals; Antibody Specificity; Brain Chemistry; Cerebellum/anatomy & histology; Cerebellum/cytology; Cerebellum/metabolism; Immunoblotting; Immunohistochemistry; In Situ Hybridization; Mice; Mice, Knockout; RNA, Messenger/analysis; Receptors, N-Methyl-D-Aspartate/analysis; Receptors, N-Methyl-D-Aspartate/genetics; Receptors, N-Methyl-D-Aspartate/immunology; Receptors, N-Methyl-D-Aspartate/metabolism; Receptors, N-Methyl-D-Aspartate/physiology; Synapses/chemistry; Synapses/metabolism
edit table

Annotations

Gene product	Qualifier	GO ID	GO term name	Evidence Code	with/from	Aspect	Notes	Status
edit table

References

See Help:References for how to manage references in GONUTS.