Structural mapping of patient-associated KCNMA1 gene variants.

KCNMA1-linked channelopathy is a neurological disorder characterized by seizures, motor abnormalities, and neurodevelopmental disabilities. The disease mechanisms are predicted to result from alterations in KCNMA1-encoded BK K channel activity; however, only a subset of the patient-associated variants have been functionally studied. The localization of these variants within the tertiary structure or evaluation by pathogenicity algorithms has not been systematically assessed.

Structural mapping of patient-associated gene variants.

KCNMA1-linked channelopathy is a neurological disorder characterized by seizures, motor abnormalities, and neurodevelopmental disabilities. The disease mechanisms are predicted to result from alterations in KCNMA1-encoded BK channel activity; however, only a subset of the patient-associated variants have been functionally studied. The localization of these variants within the tertiary structure or evaluation by pathogenicity algorithms has not been systematically assessed.

Effect of an autism-associated variant, G124R, on BK channel properties.

BK K channels are critical regulators of neuron and muscle excitability, comprised of a tetramer of pore-forming αsubunits from the gene and cell- and tissue-selective β subunits (). Mutations in are associated with neurological disorders, including autism. However, little is known about the role of neuronal BK channel β subunits in human neuropathology.

BK channel properties correlate with neurobehavioral severity in three -linked channelopathy mouse models.

KCNMA1 forms the pore of BK K channels, which regulate neuronal and muscle excitability. Recently, genetic screening identified heterozygous variants in a subset of patients with debilitating paroxysmal non-kinesigenic dyskinesia, presenting with or without epilepsy (PNKD3). However, the relevance of mutations and the basis for clinical heterogeneity in PNKD3 has not been established.

An emerging spectrum of variants and clinical features in -linked channelopathy.

-linked channelopathy is an emerging neurological disorder characterized by heterogeneous and overlapping combinations of movement disorder, seizure, developmental delay, and intellectual disability. encodes the BK K channel, which contributes to both excitatory and inhibitory neuronal and muscle activity. Understanding the basis of the disorder is an important area of active investigation; however, the rare prevalence has hampered the development of large patient cohorts necessary to establish genotype-phenotype correlations.

Comparative gain-of-function effects of the -N999S mutation on human BK channel properties.

, encoding the voltage- and calcium-activated potassium channel, has a pivotal role in brain physiology. Mutations in are associated with epilepsy and/or dyskinesia (PNKD3). Two mutations correlated with these phenotypes, D434G and N999S, were previously identified as producing gain-of-function (GOF) effects on BK channel activity.

-linked channelopathy.

encodes the pore-forming α subunit of the "Big K" (BK) large conductance calcium and voltage-activated K channel. BK channels are widely distributed across tissues, including both excitable and nonexcitable cells. Expression levels are highest in brain and muscle, where BK channels are critical regulators of neuronal excitability and muscle contractility.

Trans-toxin ion-sensitivity of charybdotoxin-blocked potassium-channels reveals unbinding transitional states.

In silico and in vitro studies have made progress in understanding protein-protein complex formation; however, the molecular mechanisms for their dissociation are unclear. Protein-protein complexes, lasting from microseconds to years, often involve induced-fit, challenging computational or kinetic analysis. Charybdotoxin (CTX), a peptide from the scorpion venom, blocks voltage-gated K-channels in a unique example of binding/unbinding simplicity.

Gating-induced large aqueous volumetric remodeling and aspartate tolerance in the voltage sensor domain of Shaker K channels.

Neurons encode electrical signals with critically tuned voltage-gated ion channels and enzymes. Dedicated voltage sensor domains (VSDs) in these membrane proteins activate coordinately with an unresolved structural change. Such change conveys the transmembrane translocation of four positively charged arginine side chains, the voltage-sensing residues (VSRs; R1-R4).

Pore size matters for potassium channel conductance.

Ion channels are membrane proteins that mediate efficient ion transport across the hydrophobic core of cell membranes, an unlikely process in their absence. K(+) channels discriminate K(+) over cations with similar radii with extraordinary selectivity and display a wide diversity of ion transport rates, covering differences of two orders of magnitude in unitary conductance. The pore domains of large- and small-conductance K(+) channels share a general architectural design comprising a conserved narrow selectivity filter, which forms intimate interactions with permeant ions, flanked by two wider vestibules toward the internal and external openings.

Biophysical analysis of thermosensitive TRP channels with a special focus on the cold receptor TRPM8.

Mammals maintain homeostatic control of their body temperature. Therefore, these organisms are expected to have adaptations that confer the ability to detect and react to both self and ambient temperature. Temperature-activated ion channels have been discovered to be the primary molecular determinants of thermosensation.

Effective pore size and radius of capture for K(+) ions in K-channels.

Reconciling protein functional data with crystal structure is arduous because rare conformations or crystallization artifacts occur. Here we present a tool to validate the dimensions of open pore structures of potassium-selective ion channels. We used freely available algorithms to calculate the molecular contour of the pore to determine the effective internal pore radius (r(E)) in several K-channel crystal structures.

The pore-domain of TRPA1 mediates the inhibitory effect of the antagonist 6-methyl-5-(2-(trifluoromethyl)phenyl)-1H-indazole.

The transient receptor potential ion channel TRPA1 confers the ability to detect tissue damaging chemicals to sensory neurons and as a result mediates chemical nociception in vivo. Mouse TRPA1 is activated by electrophilic compounds such as mustard-oil and several physical stimuli such as cold temperature. Due to its sensory function inhibition of TRPA1 activity might provide an effective treatment against chronic and inflammatory pain.

Directionality of temperature activation in mouse TRPA1 ion channel can be inverted by single-point mutations in ankyrin repeat six.

Several transient receptor potential (TRP) ion channels are activated with high sensitivity by either cold or hot temperatures. However, structures and mechanism that determine temperature directionality (cold versus heat) are not established. Here we screened 12,000 random mutant clones of the cold-activated mouse TRPA1 ion channel with a heat stimulus.

Fast and reversible stimulation of astrocytic glycolysis by K+ and a delayed and persistent effect of glutamate.

Synaptic activity is followed within seconds by a local surge in lactate concentration, a phenomenon that underlies functional magnetic resonance imaging and whose causal mechanisms are unclear, partly because of the limited spatiotemporal resolution of standard measurement techniques. Using a novel Förster resonance energy transfer-based method that allows real-time measurement of the glycolytic rate in single cells, we have studied mouse astrocytes in search for the mechanisms responsible for the lactate surge. Consistent with previous measurements with isotopic 2-deoxyglucose, glutamate was observed to stimulate glycolysis in cultured astrocytes, but the response appeared only after a lag period of several minutes.

Kinetic validation of 6-NBDG as a probe for the glucose transporter GLUT1 in astrocytes.

In recent years, the use of fluorescent glucose analogs has allowed the study of rapid transport modulation in heterogeneous cell cultures and complex tissues. However, the kinetic behavior of these tracers is not conventional. For instance, the fluorescent glucose analog 6-NBDG permeates the cell 50-100 times slower than glucose but the uptake of 6-NBDG is almost insensitive to glucose, an observation that casts doubts as to the specificity of the uptake pathway.