Insights into the Structural Basis for Zinc Inhibition of the Glycine Receptor

Nevin, Simon T.; Cromer, Brett A.; Haddrill, Justine L.; Morton, Craig J.; Parker, Michael W.; Lynch, Joseph W.

doi:10.1074/jbc.m300097200

Cited by 55 publications

(84 citation statements)

References 43 publications

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“…GlyR Structural Modeling and Computational Docking-A homology model of the ␣1 GlyR pentamer was built based on a hybrid template, with the TMD and Cys-loop based on the bacterial ELIC channel structure (Protein Data Bank code 2VL0) (15) and the remainder of the LBD based on acetylcholinebinding protein (Protein Data Bank code 1I9B) (16), as described previously (17). Two distinctly different families of ivermectin conformers were predicted by MarvinSketch software (Chemaxon, Budapest, Hungary).…”

Section: Methodsmentioning

confidence: 99%

“…Assuming subunits recombine randomly to produce receptors with all possible stoichiometries, the number of putative intersubunit ivermectin sites (i.e. interfaces containing Gly 288 on one face and Pro 230 on the other) will range from 0 to 2 per receptor (17). As shown in the example in Fig.…”

Section: Disruption Of Ivermectin Efficacy Via Mutations At the Lbd-tmdmentioning

confidence: 99%

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Molecular Determinants of Ivermectin Sensitivity at the Glycine Receptor Chloride Channel

Lynagh

Webb

Dixon

et al. 2011

Journal of Biological Chemistry

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Section: Methodsmentioning

confidence: 99%

Section: Disruption Of Ivermectin Efficacy Via Mutations At the Lbd-tmdmentioning

confidence: 99%

Molecular Determinants of Ivermectin Sensitivity at the Glycine Receptor Chloride Channel

Lynagh

Webb

Dixon

et al. 2011

Journal of Biological Chemistry

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“…This region coincides with residues that have been shown to bind Ca 2+ in AChBP (Brejc et al 2001). Zinc-binding sites have been located at subunit interfaces in nAChR and GlyR (Hsiao et al 2006 ;Nevin et al 2003), while in GABA A receptors, zinc binds to both the ECD and the pore (Dunne et al 2002 ;Fisher & Macdonald, 1998 ;Fisher, 2002 ;Horenstein & Akabas, 1998 ;Hosie et al 2003). Binding of these ions is likely to have important physiological consequences although these are not yet fully understood.…”

Section: Ions As Modulatorsmentioning

confidence: 99%

The structural basis of function in Cys-loop receptors

Thompson

Lester

Lummis

2010

Quart. Rev. Biophys.

326

398

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Abstract. Cys-loop receptors are membrane-spanning neurotransmitter-gated ion channels that are responsible for fast excitatory and inhibitory transmission in the peripheral and central nervous systems. The best studied members of the Cys-loop family are nACh, 5-HT 3 , GABA A and glycine receptors. All these receptors share a common structure of five subunits, pseudo-symmetrically arranged to form a rosette with a central ion-conducting pore. Some are cation selective (e.g. nACh and 5-HT 3 ) and some are anion selective (e.g. GABA A and glycine). Each receptor has an extracellular domain (ECD) that contains the ligand-binding sites, a transmembrane domain (TMD) that allows ions to pass across the membrane, and an intracellular domain (ICD) that plays a role in channel conductance and receptor modulation. Cys-loop receptors are the targets for many currently used clinically relevant drugs (e.g. benzodiazepines and anaesthetics). Understanding the molecular mechanisms of these receptors could therefore provide the catalyst for further development in this field, as well as promoting the development of experimental techniques for other areas of neuroscience.In this review, we present our current understanding of Cys-loop receptor structure and function. The ECD has been extensively studied. Research in this area has been stimulated in recent years by the publication of high-resolution structures of nACh receptors and related proteins, which have permitted the creation of many Cys loop receptor homology models of this region. Here, using the 5-HT 3 receptor as a typical member of the family, we describe how homology modelling and ligand docking can provide useful but not definitive information about ligand interactions. We briefly consider some of the many Cys-loop receptors modulators. We discuss the current understanding of the structure of the TMD, and how this links to the ECD to allow channel gating, and consider the roles of the ICD, whose structure is poorly understood. We also describe some of the current methods that are beginning to reveal the differences between different receptor states, and may ultimately show structural details of transitions between them.

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“…Alternatively, the histidines between adjacent subunits could form an intersubunit binding site, as is the case for ␥-aminobutyric acid type A receptors (18) and glycine receptors (19). A recent study using cross-linking to study the extracellular loop of P2X 2 receptors (20) established that the N-terminal end of one loop is in close proximity to the C-terminal end of the loop of an adjacent subunit, as might be expected if His 120 and His 213 form an intersubunit zinc binding site.…”

Section: Intersubunit Interactions Are Required For Zinc Potentiation-ifmentioning

confidence: 99%

An Intersubunit Zinc Binding Site in Rat P2X2 Receptors

Nagaya

Tittle

Saar

et al. 2005

Journal of Biological Chemistry

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P2X receptors are ATP-gated ion channels made up of three similar or identical subunits. It is unknown whether ligand binding is intersubunit or intrasubunit, either for agonists or for allosteric modulators. Zinc binds to rat P2X 2 receptors and acts as an allosteric modulator, potentiating channel opening. To probe the location of this zinc binding site, P2X 2 receptors bearing mutations of the histidines at positions 120 and 213 were expressed in Xenopus oocytes. Studies of H120C and H213C mutants produced five lines of evidence consistent with the hypothesis that the residues in these positions bind zinc. Mixing of subunits containing the H120A or H213A mutation generated receptors that showed zinc potentiation, even though neither of these mutant receptors showed zinc potentiation on its own. Furthermore, expression of trimeric concatamers with His 3 Ala mutations at some but not all six positions showed that zinc potentiation correlated with the number of intersubunit histidine pairs. These results indicate that zinc potentiation requires an interaction across a subunit interface. Expression of the H120C/H213C double mutant resulted in the formation of ectopic disulfide bonds that could be detected by changes in the physiological properties of the receptors after treatment with reducing and oxidizing agents. Immunoblot analysis of H120C/H213C protein separated under nonreducing conditions demonstrated that the ectopic bonds were between adjacent subunits. Taken together, these data indicate that His 120 and His 213 sit close to each other across the interface between subunits and are likely to be key components of the zinc binding site in P2X 2 receptors.P2X receptors are oligomeric, ATP-gated cation channels that are distributed widely throughout the central and peripheral nervous systems of mammals and are known to be involved in fast excitatory synaptic transmission (1). P2X receptors are structurally distinct from the nicotinic receptor and ionotropic glutamate receptor channel superfamilies. In mammals, the P2X family has seven members encoded by different genes (P2X 1-7 ) that can associate as homo-and heteromeric channel assemblies (1). P2X receptors are thought to be trimers (2) with subunits that have intracellular N and C termini, two transmembrane domains, and a large extracellular loop (1).Colocalization of zinc with P2X 2 receptors in the nervous system suggests a physiological role for this divalent cation in modulating ATP-evoked currents (3, 4). Extracellular zinc potentiates P2X receptor currents in rat sensory and sympathetic neurons as well as in rat PC12 cells (1). The potentiating effect of zinc on P2X 2 receptors results from a decrease in the EC 50 for ATP without a concomitant change in the maximum response to ATP (5, 6).We have previously identified two molecular determinants of zinc potentiation for the rat P2X 2 subunit (6); mutation of either His 120 or His 213 to alanine eliminated potentiation by zinc. Direct participation of these residues in zinc binding is consistent with t...

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Insights into the Structural Basis for Zinc Inhibition of the Glycine Receptor

Cited by 55 publications

References 43 publications

Molecular Determinants of Ivermectin Sensitivity at the Glycine Receptor Chloride Channel

Molecular Determinants of Ivermectin Sensitivity at the Glycine Receptor Chloride Channel

The structural basis of function in Cys-loop receptors

An Intersubunit Zinc Binding Site in Rat P2X2 Receptors

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