Acetylcholine receptor assembly: Subunit folding and oligomerization occur sequentially

Green, William N.; Claudio, Toni

doi:10.1016/0092-8674(93)90294-z

Cited by 142 publications

(164 citation statements)

References 32 publications

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“…ER exit serves as an important checkpoint both in coordinating the sequential assembly of multisubunit protein complexes within the ER and in defining the number of receptors expressed at the plasma membrane (Blount et al, 1990;Green and Claudio, 1993;Brodsky and McCracken, 1999;Ellgaard et al, 1999;Zerangue et al, 1999;Bichet et al, 2000;Margeta-Mitrovic et al, 2000). Here we have provided a first description of ER quality control mechanisms that regulate the plasma membrane delivery of NMDA receptors.…”

Section: Discussionmentioning

confidence: 99%

An NMDA Receptor ER Retention Signal Regulated by Phosphorylation and Alternative Splicing

et al. 2001

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Formation of mature excitatory synapses requires the assembly and delivery of NMDA receptors to the neuronal plasma membrane. A key step in the trafficking of NMDA receptors to synapses is the exit of newly assembled receptors from the endoplasmic reticulum (ER). Here we report the identification of an RXR-type ER retention/retrieval motif in the C-terminal tail of the NMDA receptor subunit NR1 that regulates receptor surface expression in heterologous cells and in neurons. In addition, we show that PKC phosphorylation and an alternatively spliced consensus type I PDZ-binding domain suppress ER retention. These results demonstrate a novel quality control function for alternatively spliced C-terminal domains of NR1 and implicate both phosphorylation and potential PDZ-mediated interactions in the trafficking of NMDA receptors through early stages of the secretory pathway.

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Section: Discussionmentioning

confidence: 99%

An NMDA Receptor ER Retention Signal Regulated by Phosphorylation and Alternative Splicing

et al. 2001

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“…It is known that the assembly of the electroplaque nicotinic receptor proceeds through the formation of trimers and tetramers and that subunit folding requires the presence of particular subunit combinations (38). It is possible, therefore, that the correct folding and subsequent assembly of the Bsubunits in the endoplasmic reticulum requires the concomitant presence of A-subunits.…”

Section: Discussionmentioning

confidence: 99%

Atomic force microscopy reveals the stoichiometry and subunit arrangement of 5-HT₃receptors

Barrera

Herbert

Henderson

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

111

104

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The 5-HT3 receptor is a cation-selective ligand-gated ion channel of the Cys-loop superfamily. The receptor is an important therapeutic target, with receptor antagonists being widely used as antiemetics in cancer therapy. The two known receptor subunits, A and B, form homomeric 5-HT 3A receptors and heteromeric 5-HT3A/B receptors. The heteromeric receptor has the higher single-channel conductance and more closely mimics the properties of the native receptor. We have used atomic force microscopy to study the architecture of 5-HT 3A and 5-HT3A/B receptors. We engineered different epitope tags onto the A-and B-subunits and imaged receptors that were doubly liganded by anti-epitope antibodies. We found that, for the 5-HT 3A/B receptor, the distribution of angles between antibodies against the A-subunit had a single peak at Ϸ144°, whereas the distribution for antibodies against the B-subunit had two peaks at Ϸ72°and 144°. Our results indicate that the subunit stoichiometry is 2A:3B and that the subunit arrangement around the receptor rosette is B-B-A-B-A. This arrangement may account for the difference between the agonist Hill coefficients and the single-channel conductances for the two types of receptor.ligand-gated ion channel ͉ receptor structure T he 5-HT 3 receptor is a member of the Cys-loop ligand-gated ion channel superfamily, together with the nicotinic acetylcholine receptor, the GABA A receptor, and the glycine receptor (1-3). Electron microscopy of the affinity purified 5-HT 3 receptor has shown that it contains five subunits arranged pseudosymmetrically around a cylinder of long axis 11 nm and external diameter 8 nm (4, 5). The vestibule of the channel, normally open to the cell exterior, is visible as an opening of diameter 2-3 nm. Two 5-HT 3 receptor subunits have been investigated in detail. The first to be cloned, 5-HT 3A (6), expresses as a functional homomer, whereas the second, 5-HT 3B , is unable to form functional channels alone but expresses robustly in the presence of the 5-HT 3A subunit (7). The genes for these two subunits are located in close proximity on chromosome 11, although additional putative 5-HT 3 receptor genes have been isolated on chromosome 3 (8). The biophysical properties of the 5-HT 3A and the 5-HT 3A/B receptors exhibit significant differences, with those of the heteromer more closely resembling those of the receptor characterized within the majority of mammalian systems (9-12). Competitive antagonists of 5-HT 3 receptors are used clinically as antiemetics in cancer chemotherapy and in general anesthesia, although other applications are being explored (13). The two receptor subtypes are difficult to distinguish pharmacologically (14), although picrotoxin (15) and tubocurarine (7) are markedly less potent in blocking agonist-induced currents in the exogenously expressed heteromeric receptors. Although there is some anatomical evidence that the homomeric receptor may be expressed alone in the rat (16, 17), current functional evidence suggests that it is the heteromer that is o...

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“…The subunits of these proteins are cotranslationally inserted into the membrane, lumen, or both, of the endoplasmic reticulum, after which the subunits fold and oligomerize (Verrall and Hall, 1992;Green and Claudio, 1993;Connolly et al, 1996a;Griffon et al, 1999). During these folding and oligomerization events, each subunit must recognize its neighbors by specific high-affinity interactions.…”

Section: Abstract: Gaba a Receptor; Assembly; Subunit Interface; Strmentioning

confidence: 99%

Alternate Use of Distinct Intersubunit Contacts Controls GABA_AReceptor Assembly and Stoichiometry

et al. 2001

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GABA A receptors are the major inhibitory transmitter receptors in the CNS. Recombinant GABA A receptors composed of ␣ 1 ␤ 3 ␥ 2 subunits have been demonstrated to assemble as pentamers consisting of two ␣ 1 , two ␤ 3 , and one ␥ 2 subunit. Using truncated and chimeric ␣ 1 subunits, we identified the ␣ 1 (80-100) sequence as a major binding site for ␥ 2 subunits. In addition, we demonstrated its direct interaction with ␥ 2 (91-104), a sequence that previously has been identified to form the contact to ␣ 1 subunits. The observation that the amino acid residues ␣ 1 P96 and ␣ 1 H101, which can be photolabeled by [ 3 H]flunitrazepam, are located within or adjacent to the ␣ 1 (80-100) sequence, indicates that the benzodiazepine binding site of GABA A receptors is located close to this intersubunit contact. The observation that ␣ 1 (80-100) interacts with ␥ 2 but not with ␤ 3 subunits indicates the existence of an additional ␤ 3 binding site on ␣ 1 subunits. The preferred alternate use of the ␥ 2 and ␤ 3 binding sites in two different ␣ 1 subunits of the same receptor ensures the incorporation of only a single ␥ 2 subunit and thus, determines subunit stoichiometry of ␣ 1 ␤ 3 ␥ 2 receptors. Distinct binding sites and their alternate use can therefore explain how subunits of hetero-oligomeric transmembrane proteins assemble into a defined protein complex.

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Acetylcholine receptor assembly: Subunit folding and oligomerization occur sequentially

Cited by 142 publications

References 32 publications

An NMDA Receptor ER Retention Signal Regulated by Phosphorylation and Alternative Splicing

An NMDA Receptor ER Retention Signal Regulated by Phosphorylation and Alternative Splicing

Atomic force microscopy reveals the stoichiometry and subunit arrangement of 5-HT₃receptors

Alternate Use of Distinct Intersubunit Contacts Controls GABA_AReceptor Assembly and Stoichiometry

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Acetylcholine receptor assembly: Subunit folding and oligomerization occur sequentially

Cited by 142 publications

References 32 publications

An NMDA Receptor ER Retention Signal Regulated by Phosphorylation and Alternative Splicing

An NMDA Receptor ER Retention Signal Regulated by Phosphorylation and Alternative Splicing

Atomic force microscopy reveals the stoichiometry and subunit arrangement of 5-HT3receptors

Alternate Use of Distinct Intersubunit Contacts Controls GABAAReceptor Assembly and Stoichiometry

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Atomic force microscopy reveals the stoichiometry and subunit arrangement of 5-HT₃receptors

Alternate Use of Distinct Intersubunit Contacts Controls GABA_AReceptor Assembly and Stoichiometry