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Mechanisms of channel block in calcium-permeable AMPA receptors

Published on 08.16.2018 in Neuron

Authors: Edward C. Twomey, Maria V. Yelshanskaya, Alexander A. Vassilevski, Alexander I. Sobolevsky

We determined the structures of calcium-permeable GluA2 AMPA receptor complexes with the auxiliary subunit stargazin bound to channel blockers, including the orb weaver spider toxin AgTx-636, the spider toxin analog NASPM, and the adamantane derivative IEM-1460. Our structures provide insights into the architecture of the blocker binding site and the mechanism of trapping block.

Taylor and Francis

X-ray crystallography of TRP channels

Published on 04.30.2018 in Channels

Authors: Appu K. Singh, Luke L. McGoldrick, Kei Saotome, Alexander I. Sobolevsky  

Transient receptor potential (TRP) ion channels are molecular sensors of a large variety of stimuli including temperature, mechanical stress, voltage, small molecules including capsaicin and menthol, and lipids such as phosphatidylinositol 4,5-bisphosphate (PIP2). Since the same TRP channels may respond to different physical and chemical stimuli, they can serve as signal integrators.

Scientific Reports

Ion permeation mechanism in epithelial calcium channel TRVP6

Published on 04.09.2018 in Scientific Reports

Authors: Serzhan Sakipov, Alexander I. SobolevskyMaria G. Kurnikova

At low Ca2+ concentrations, only a single calcium ion binds at the narrow constriction of the TRPV6 selectivity filter formed by aspartates D541 and allows Na+ permeation. During ion permeation, no water crosses the channel pore narrow constriction. At high Ca2+ concentrations, calcium permeates the pore according to the knock-off mechanism that includes formation of a short-lived transition state with three calcium ions bound near D541.

British Pharmacological Society

Proton-independent activation of acid-sensing ion channel 3 by an alkaloid, lindoldhamine, from Laurus nobilis

Published on 12.26.2017 in British Journal of Pharmacology

Authors: Dmitry I. Osmakov, Sergey G. Koshelev, Yaroslav A. Andreev, Maxim A. Dubinnyi, Vadim S. Kublitski, Roman G. Efremov, Alexander I. Sobolevsky, Sergey A. Kozlov

At pH 7.4 or higher, LIN activated a sustained, proton-independent, current through rat and human ASIC3 channels, but not rat ASIC1a or ASIC2a channels. LIN also potentiated proton-induced transient currents and promoted recovery from desensitization in human, but not rat, ASIC3 channels.


Opening of the human epithelial calcium channel TRPV6

Published on 12.20.2017 in Nature

Authors: Luke L. McGoldrick*, Appu K. Singh*, Kei Saotome, Maria V. Yelshanskaya, Edward C. Twomey, Robert A. GrassucciAlexander I. Sobolevsky

Here we present cryo-electron microscopy structures of human TRPV6 in the open and closed states. The channel selectivity filter adopts similar conformations in both states, consistent with its explicit role in ion permeation. The iris-like channel opening is accompanied by an α-to-π-helical transition in the pore-lining transmembrane helix S6 at an alanine hinge just below the selectivity filter.


Structural mechanisms of gating in ionotropic glutamate receptors

Published on 10.16.2017 in Biochemistry

Authors: Edward C. TwomeyAlexander I. Sobolevsky

Ionotropic glutamate receptors (iGluRs) are ligand-gated ion channels that mediate the majority of excitatory neurotransmission in the central nervous system. iGluRs open their ion channels in response to binding of the neurotransmitter glutamate, rapidly depolarize the postsynaptic neuronal membrane, and initiate signal transduction.

Scientific Reports

Swapping of transmembrane domains in the epithelial calcium channel TRPV6

Published on 09.06.2017 in Scientific Reports

Authors: Appu K. Singh, Kei SaotomeAlexander I. Sobolevsky

Here we show that mutations in the transmembrane domain of TRPV6 can result in conversion from a domain-swapped to non-swapped fold. These results reveal structural determinants of domain swapping and raise the possibility that a single ion channel subtype can fold into either arrangement in vivo, affecting its function in normal or disease states.

Taylor and Francis

Determining the crystal structure of TRPV6

Published on 06.08.2017 in Calcium Entry Channels in Non-Excitable Cells

Authors: Appu K. Singh, Kei Saotome, Alexander I. Sobolevsky  

The concept of signal transduction is now long established as a central tenet of biological sciences. Since the inception of the field close to 50 years ago, the number and variety of signal transduction pathways, cascades, and networks have steadily increased and now constitute what is often regarded as a bewildering array of mechanisms by which cells sense and respond to extracellular and intracellular environmental stimuli.


Structural bases of desensitization in AMPA receptor-auxiliary subunit complexes

Published on 05.03.2017 in Neuron

Authors: Edward C. Twomey, Maria V. Yelshanskaya, Robert A. Grassucci, Joachim FrankAlexander I. Sobolevsky

Here, we report cryo-EM structures of an AMPAR in complex with the auxiliary subunit GSG1L in the closed and desensitized states. GSG1L favors the AMPAR desensitized state, where channel closure is facilitated by profound structural rearrangements in the AMPAR extracellular domain, with ligand-binding domain dimers losing their local 2-fold rotational symmetry.

Scientific Reports

Role of the ion channel extracellular collar in AMPA receptor gating

Published on 04.21.2017 in Scientific Reports

Authors: Maria V. Yelshanskaya, Samaneh Mesbahi-Vasey, Maria G. KurnikovaAlexander I. Sobolevsky

We used site-directed mutagenesis and patch-clamp recordings to probe the ion channel extracellular collar, the binding region for noncompetitive allosteric inhibitors. We found position and substitution-dependent effects for introduced mutations at this region on AMPA receptor gating.


Structural bases of noncompetitive inhibition of AMPA-subtype ionotropic glutamate receptors by antiepileptic drugs

Published on 09.08.2016 in Neuron

Authors: Maria V. Yelshanskaya, Appu K. Singh, Jared M. Sampson, Chamali Narangoda, Maria Kurnikova, Alexander I. Sobolevsky

Here, we report crystal structures of the rat AMPA-subtype GluA2 receptor in complex with three noncompetitive inhibitors. The inhibitors bind to a novel binding site, completely conserved between rat and human, at the interface between the ion channel and linkers connecting it to the ligand-binding domains. We propose that the inhibitors stabilize the AMPA receptor closed state.


Elucidation of AMPA receptor-stargazin complexes by cryo-electron microscopy

Published on 07.01.2016 in Science

Authors: Edward C. Twomey, Maria V. Yelshanskaya, Robert A. Grassucci, Joachim Frank, Alexander I. Sobolevsky

Here, we used cryo-electron microscopy to elucidate the structural basis of AMPAR regulation by one of these auxiliary proteins, TARP γ2, or stargazin (STZ). Our structures illuminate the variable interaction stoichiometry of the AMPAR-TARP complex, with one or two TARP molecules binding one tetrameric AMPAR.


Expression, purification, and crystallization of full length ionotropic glutamate receptors

Published on 01.07.2016 in Neuromethods

Authors: Maria V. Yelshanskaya, Kei Saotome, Minfen Li, Alexander I. Sobolevsky

Despite physiological and pathophysiological importance, obtaining structural information about full-length iGluRs has proven to be a difficult task. To facilitate further structural/functional studies, we describe a detailed protocol of the full-length iGluR expression, purification, and crystallization.


Structure of an agonist-bound ionotropic glutamate receptor

Published on 08.29.2014 in Science

Authors: Maria V. Yelshanskaya, Minfen Li, Alexander I. Sobolevsky

Here, we report a structure of a homotetrameric rat GluA2 receptor in complex with partial agonist (S)-5-nitrowillardiine. Comparison of this structure with the closed-state structure in complex with competitive antagonist ZK 200775 suggests conformational changes that occur during iGluR gating.


Sobolevsky Lab publication list

Published on 1998-2018 in PubMed

Authors: Alexander I. Sobolevsky

Based in the Department of Biochemistry and Molecular Biophysics at Columbia University Medical Center, we study ion channel signaling using cryo-electron microscopy, X-ray crystallography, electrophysiology and biophysical techniques.