@article {2016|1672,
	title = {A Novel Bifunctional Alkylphenol Anesthetic Allows Characterization of gamma-Aminobutyric Acid, Type A (GABAA), Receptor Subunit Binding Selectivity in Synaptosomes.},
	journal = {J. Biol. Chem},
	volume = {291},
	year = {2016},
	month = {sep},
	pages = {20473{\textendash}86},
	abstract = {<p>Propofol, an intravenous anesthetic, is a positive modulator of the GABAA receptor, but the mechanistic details, including the relevant binding sites and alternative targets, remain disputed. Here we undertook an in-depth study of alkylphenol-based anesthetic binding to synaptic membranes. We designed, synthesized, and characterized a chemically active alkylphenol anesthetic (2-((prop-2-yn-1-yloxy)methyl)-5-(3-(trifluoromethyl)-3H-diazirin-3-yl)phenol, AziPm-click (1)), for affinity-based protein profiling (ABPP) of propofol-binding proteins in their native state within mouse synaptosomes. The ABPP strategy captured approximately 4\% of the synaptosomal proteome, including the unbiased capture of five alpha or beta GABAA receptor subunits. Lack of gamma2 subunit capture was not due to low abundance. Consistent with this, independent molecular dynamics simulations with alchemical free energy perturbation calculations predicted selective propofol binding to interfacial sites, with higher affinities for alpha/beta than gamma-containing interfaces. The simulations indicated hydrogen bonding is a key component leading to propofol-selective binding within GABAA receptor subunit interfaces, with stable hydrogen bonds observed between propofol and alpha/beta cavity residues but not gamma cavity residues. We confirmed this by introducing a hydrogen bond-null propofol analogue as a protecting ligand for targeted-ABPP and observed a lack of GABAA receptor subunit protection. This investigation demonstrates striking interfacial GABAA receptor subunit selectivity in the native milieu, suggesting that asymmetric occupancy of heteropentameric ion channels by alkylphenol-based anesthetics is sufficient to induce modulation of activity.</p>},
	keywords = {anesthesia, anesthetic, click chemistry, GABA receptor, photoaffinity labeling},
	doi = {10.1074/jbc.M116.736975},
	author = {Woll, Kellie A. and Murlidaran, Sruthi and Pinch, Benika J. and J{\'e}r{\^o}me H{\'e}nin and Wang, Xiaoshi and Salari, Reza and Covarrubias, Manuel and Dailey, William P. and Grace Brannigan and Garcia, Benjamin A. and Roderic G Eckenhoff}
}
@article {2014|1598,
	title = {A predicted binding site for cholesterol on the GABAA receptor.},
	journal = {Biophys. J.},
	volume = {106},
	number = {9},
	year = {2014},
	month = {may},
	pages = {1938{\textendash}1949},
	publisher = {Department of Physics, Rutgers University-Camden, Camden, New Jersey; Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, New Jersey. Electronic address: Grace.Brannigan@rutgers.edu.},
	abstract = {Modulation of the GABA type A receptor (GABAAR) function by cholesterol and other steroids is documented at the functional level, yet its structural basis is largely unknown. Current data on structurally related modulators suggest that cholesterol binds to subunit interfaces between transmembrane domains of the GABAAR. We construct homology models of a human GABAAR based on the structure of the glutamate-gated chloride channel GluCl of Caenorhabditis elegans. The models show the possibility of previously unreported disulfide bridges linking the M1 and M3 transmembrane helices in the α and γ subunits. We discuss the biological relevance of such disulfide bridges. Using our models, we investigate cholesterol binding to intersubunit cavities of the GABAAR transmembrane domain. We find that very similar binding modes are predicted independently by three approaches: analogy with ivermectin in the GluCl crystal structure, automated docking by AutoDock, and spontaneous rebinding events in unbiased molecular dynamics simulations. Taken together, the models and atomistic simulations suggest a somewhat flexible binding mode, with several possible orientations. Finally, we explore the possibility that cholesterol promotes pore opening through a wedge mechanism.},
	keywords = {Amino Acid, Binding Sites, Caenorhabditis elegans Proteins, chemistry, chemistry/metabolism, Chloride Channels, Cholesterol, GABA-A, Humans, Hydrogen Bonding, Ivermectin, metabolism, Molecular Docking Simulation, Molecular Dynamics Simulation, Porosity, Protein Binding, Protein Conformation, Receptors, Sequence Homology, Substrate Specificity},
	doi = {10.1016/j.bpj.2014.03.024},
	author = {J{\'e}r{\^o}me H{\'e}nin and Salari, Reza and Murlidaran, Sruthi and Grace Brannigan}
}
