Visualizing structural transitions of ligand-dependent gating of the TRPM2 channel.

The transient receptor potential melastatin 2 (TRPM2) channel plays a key role in redox sensation in many cell types. Channel activation requires binding of both ADP-ribose (ADPR) and Ca. The recently published TRPM2 structures from Danio rerio in the ligand-free and the ADPR/Ca-bound conditions represent the channel in closed and open states, which uncovered substantial tertiary and quaternary conformational rearrangements.

Regulatory switch at the cytoplasmic interface controls TRPV channel gating.

Temperature-sensitive transient receptor potential vanilloid (thermoTRPV) channels are activated by ligands and heat, and are involved in various physiological processes. ThermoTRPV channels possess a large cytoplasmic ring consisting of N-terminal ankyrin repeat domains (ARD) and C-terminal domains (CTD). The cytoplasmic inter-protomer interface is unique and consists of a CTD coiled around a β-sheet which makes contacts with the neighboring ARD.

Conformational ensemble of the human TRPV3 ion channel.

Transient receptor potential vanilloid channel 3 (TRPV3), a member of the thermosensitive TRP (thermoTRPV) channels, is activated by warm temperatures and serves as a key regulator of normal skin physiology through the release of pro-inflammatory messengers. Mutations in trpv3 have been identified as the cause of the congenital skin disorder, Olmsted syndrome. Unlike other members of the thermoTRPV channel family, TRPV3 sensitizes upon repeated stimulation, yet a lack of structural information about the channel precludes a molecular-level understanding of TRPV3 sensitization and gating.

Structure of the cold- and menthol-sensing ion channel TRPM8.

Transient receptor potential melastatin (TRPM) cation channels are polymodal sensors that are involved in a variety of physiological processes. Within the TRPM family, member 8 (TRPM8) is the primary cold and menthol sensor in humans. We determined the cryo-electron microscopy structure of the full-length TRPM8 from the collared flycatcher at an overall resolution of ~4.

Cryo-electron microscopy structure of the lysosomal calcium-permeable channel TRPML3.

The modulation of ion channel activity by lipids is increasingly recognized as a fundamental component of cellular signalling. The transient receptor potential mucolipin (TRPML) channel family belongs to the TRP superfamily and is composed of three members: TRPML1-TRPML3. TRPMLs are the major Ca-permeable channels on late endosomes and lysosomes (LEL).

Conformational changes at cytoplasmic intersubunit interactions control Kir channel gating.

The defining structural feature of inward-rectifier potassium (Kir) channels is the unique Kir cytoplasmic domain. Recently we showed that salt bridges located at the cytoplasmic domain subunit interfaces (CD-Is) of eukaryotic Kir channels control channel gating via stability of a novel inactivated closed state. The cytoplasmic domains of prokaryotic and eukaryotic Kir channels show similar conformational rearrangements to the common gating ligand, phosphatidylinositol bisphosphate (PIP), although these exhibit opposite coupling to opening and closing transitions.

Control of Kir channel gating by cytoplasmic domain interface interactions.

Inward rectifier potassium (Kir) channels are expressed in almost all mammalian tissues and play critical roles in the control of excitability. Pancreatic ATP-sensitive K (K) channels are key regulators of insulin secretion and comprise Kir6.2 subunits coupled to sulfonylurea receptors.

Structural dynamics of potassium-channel gating revealed by single-molecule FRET.

Crystallography has provided invaluable insights regarding ion-channel selectivity and gating, but to advance understanding to a new level, dynamic views of channel structures within membranes are essential. We labeled tetrameric KirBac1.1 potassium channels with single donor and acceptor fluorophores at different sites and then examined structural dynamics within lipid membranes by single-molecule fluorescence resonance energy transfer (FRET).

Kinetic contributions to gating by interactions unique to N-methyl-D-aspartate (NMDA) receptors.

Among glutamate-gated channels, NMDA receptors produce currents that subside with unusually slow kinetics, and this feature is essential to the physiology of central excitatory synapses. Relative to the homologous AMPA and kainate receptors, NMDA receptors have additional intersubunit contacts in the ligand binding domain that occur at both conserved and non-conserved sites. We examined GluN1/GluN2A single-channel currents with kinetic analyses and modeling to probe these class-specific intersubunit interactions for their role in glutamate binding and receptor gating.

Gating reaction mechanism of neuronal NMDA receptors.

The activation mechanisms of recombinant N-methyl-d-aspartate receptors (NRs) have been established in sufficient detail to account for their single channel and macroscopic responses; however, the reaction mechanism of native NRs remains uncertain due to indetermination of the isoforms expressed and possible neuron-specific factors. To delineate the activation mechanism of native NRs, we examined the kinetic properties of currents generated by individual channels located at the soma of cultured rat neurons. Cells were dissociated from the embryonic cerebral cortex or hippocampus, and on-cell single channel recordings were done between 4 and 50 days in vitro (DIV).

NMDA receptor activation requires remodelling of intersubunit contacts within ligand-binding heterodimers.

Two classes of glutamate-activated channels mediate excitation at central synapses: N-methyl-D-aspartic acid (NMDA) receptors and non-NMDA receptors. Despite substantial structural homology, each class generates signals with characteristic kinetics and mediates distinct synaptic functions. In non-NMDA receptors, the strength of intersubunit contacts within ligand-binding domains is inversely correlated with functional desensitization.