NMDA receptors (NMDARs) comprise a subclass of neurotransmitter receptors whose surface expression is regulated at multiple levels, including processing in the endoplasmic reticulum (ER), intracellular trafficking via the Golgi apparatus, internalization, recycling, and degradation. With respect to early processing, NMDARs are regulated by the availability of GluN subunits within the ER, the presence of ER retention and export signals, and posttranslational modifications, including phosphorylation and palmitoylation. However, the role of N-glycosylation, one of the most common posttranslational modifications, in regulating NMDAR processing has not been studied in detail. Using biochemistry, confocal and electron microscopy, and electrophysiology in conjunction with a lentivirus-based molecular replacement strategy, we found that NMDARs are released from the ER only when two asparagine residues in the GluN1 subunit (Asn-203 and Asn-368) are N-glycosylated. Although the GluN2A and GluN2B subunits are also N-glycosylated, their N-glycosylation sites do not appear to be essential for surface delivery of NMDARs. Furthermore, we found that removing N-glycans from native NMDARs altered the receptor affinity for glutamate. Our results suggest a novel mechanism by which neurons ensure that postsynaptic membranes contain sufficient numbers of functional NMDARs.

• Klíčová slova
• endoplasmic reticulum (ER), glutamate receptor, glycosylation, neuron, synapse, trafficking,
• MeSH
• Cercopithecus aethiops MeSH
• COS buňky MeSH
• endoplazmatické retikulum metabolismus   MeSH
• glykosylace MeSH
• Golgiho aparát metabolismus   MeSH
• HEK293 buňky MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• N-methylaspartát chemie   metabolismus   MeSH
• nervový přenos * MeSH
• neurony chemie   metabolismus   MeSH
• polysacharidy metabolismus   MeSH
• receptory N-methyl-D-aspartátu chemie   metabolismus   MeSH
• synapse metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• N-methylaspartát MeSH
• polysacharidy MeSH
• receptory N-methyl-D-aspartátu MeSH

Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system. There are three distinct subtypes of ionotropic glutamate receptors (GluRs) that have been identified including 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl)propanoic acid receptors (AMPARs), N-methyl-D-aspartate receptors (NMDARs) and kainate receptors. The most common GluRs in mature synapses are AMPARs that mediate the fast excitatory neurotransmission and NMDARs that mediate the slow excitatory neurotransmission. There have been large numbers of recent reports studying how a single neuron regulates synaptic numbers and types of AMPARs and NMDARs. Our current research is centered primarily on NMDARs and, therefore, we will focus in this review on recent knowledge of molecular mechanisms occurring (1) early in the biosynthetic pathway of NMDARs, (2) in the transport of NMDARs after their release from the endoplasmic reticulum (ER); and (3) at the plasma membrane including excitatory synapses. Because a growing body of evidence also indicates that abnormalities in NMDAR functioning are associated with a number of human psychiatric and neurological diseases, this review together with other chapters in this issue may help to enhance research and to gain further knowledge of normal synaptic physiology as well as of the etiology of many human brain diseases.

• Klíčová slova
• excitatory neurotransmission, glutamate receptor, internalization, intracellular trafficking, ion channel, subcellular compartment,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

The assembly of two covalently linked monomers into dimeric complexes is a prerequisite for metabotropic glutamate receptor 1 (mGluR1) function. The former concept of a strictly homodimeric subunit contribution in metabotropic glutamate receptor complexes has recently been brought into question. Alternative splicing of the GRM1 gene results in expression of variants that vary within their intracellular C-termini. Here we bring evidence that the short mGluR1b variant is found preferentially in a complex with the long mGluR1a variant in the rodent brain. The mGluR1a and mGluR1b variants distribution overlaps in Purkinje cells and the two variants colocalize in their spines. However mGluR1a and mGluR1b show distinct sub-cellular localization when expressed alone in neurons. We discovered that trafficking of mGluR1b to distal dendrites is reliant on its association with mGluR1a and that the long C-terminus of mGluR1a within the mGluR1a/b dimer is necessary for trafficking of the complex.

• Klíčová slova
• Alternative splicing, G-protein coupled receptors (GPCR), Metabotropic glutamate receptors, Protein–protein interactions, Trafficking,
• MeSH
• aktivní transport MeSH
• dendritické trny metabolismus   MeSH
• dimerizace MeSH
• elektroforéza v polyakrylamidovém gelu MeSH
• elektronová mikroskopie MeSH
• HEK293 buňky MeSH
• imunoblotting MeSH
• imunohistochemie MeSH
• krysa rodu Rattus MeSH
• kultivované buňky MeSH
• lidé MeSH
• mozek metabolismus   MeSH
• neurony metabolismus   MeSH
• potkani Sprague-Dawley MeSH
• potkani Wistar MeSH
• protein - isoformy MeSH
• receptory metabotropního glutamátu metabolismus   MeSH
• subcelulární frakce metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Intramural MeSH
• Názvy látek
• metabotropic glutamate receptor type 1 MeSH Prohlížeč
• protein - isoformy MeSH
• receptory metabotropního glutamátu MeSH