Structural link between γ-aminobutyric acid type A (GABAA) receptor agonist binding site and inner β-sheet governs channel activation and allosteric drug modulation.

Rapid opening and closing of pentameric ligand-gated ion channels (pLGICs) regulate information flow throughout the brain. For pLGICs, it is postulated that neurotransmitter-induced movements in the extracellular inner β-sheet trigger channel activation. Homology modeling reveals that the β4-β5 linker physically connects the neurotransmitter binding site to the inner β-sheet.

Identification of a fluorescent general anesthetic, 1-aminoanthracene.

We identified a fluorophore, 1-aminoanthracene (1-AMA), that is anesthetic, potentiates GABAergic transmission, and gives an appropriate dissociation constant, K(d) approximately 0.1 mM, for binding to the general anesthetic site in horse spleen apoferritin (HSAF). 1-AMA fluorescence is enhanced when bound to HSAF.

A conserved salt bridge critical for GABA(A) receptor function and loop C dynamics.

Chemical signaling in the brain involves rapid opening and closing of ligand gated ion channels (LGICs). LGICs are allosteric membrane proteins that transition between multiple conformational states (closed, open, and desensitized) in response to ligand binding. While structural models of cys-loop LGICs have been recently developed, our understanding of the protein movements underlying these conformational transitions is limited.

Optimized expression vector for ion channel studies in Xenopus oocytes and mammalian cells using alfalfa mosaic virus.

Plasmid vectors used for mammalian expression or for in vitro cRNA translation can differ substantially and are rarely cross-compatible. To make comparisons between mammalian and Xenopus oocyte expression systems, it would be advantageous to use a single vector without the need for shuttle vectors or subcloning. We have designed such a vector, designated pUNIV for universal, with elements that will allow for in vitro or ex vivo expression in multiple cell types.

Micromechanical measurement of membrane receptor binding for label-free drug discovery.

A potential novel binding assay based on binding-driven micromechanical motion is described. A membrane preparation containing 5-HT(3AS) receptors was used to modify a microcantilever. The modified microcantilever was found to bend on application of the naturally occurring agonist (5-hydroxytryptamine, which is also called serotonin) or the antagonist MDL-72222, but not to other similar molecules.

Identification of critical residues in loop E in the 5-HT3ASR binding site.

Background: The serotonin type 3 receptor (5-HT3R) is a member of a superfamily of ligand gated ion channels. All members of this family share a large degree of sequence homology and presumably significant structural similarity. A large number of studies have explored the structure-function relationships of members of this family, particularly the nicotinic and GABA receptors.

Functional group interactions of a 5-HT3R antagonist.

Background: Lerisetron, a competitive serotonin type 3 receptor (5-HT3R) antagonist, contains five functional groups capable of interacting with amino acids in the 5-HT3R binding site. Site directed mutagenesis studies of the 5-HT3AR have revealed several amino acids that are thought to form part of the binding domain of this receptor. The specific functional groups on the ligand that interact with these amino acids are, however, unknown.