Voltage Sensor Module Research Articles

Size‐dependent failure behavior of commercially available lithium‐iron phosphate battery under mechanical abuse

AbstractUnder mechanical abuse, the failure of lithium‐ion batteries occurs in various stages, characterized by different force, temperature, and voltage responses, and require in situ measurements for analysis. First, four sizes of commercially available lithium‐iron phosphate batteries (LFPB), namely 18650, 22650, 26650, and 32650, were subjected to quasistatic lateral and longitudinal compression and nail penetration tests. The failure, characterized by the voltage drop and temperature rise at the onset of the first internal short‐circuit (ISC), was identified by an Aurdino‐based voltage sensor module and a temperature measurement module, respectively. The battery failure load and peak temperature at the onset of ISC were found to rely strongly on the battery size. The failure was delayed for small‐sized 18650 batteries during lateral compression, unlike in longitudinal compression and nail penetration tests. At the onset of ISC, the temperature rise above the ambient value was different for different LFPBs. It was found to be maximum (36.4°C) for LFPB 32650 under longitudinal compression and minimum (1.5°C) under lateral compression tests among the considered geometries. Further, LFPB 26650 exhibited a balanced thermal behavior during the test. Such thermal response can be sensed timely for effective thermal management of lithium‐ion batteries.

Bio-FET Sensor Interface Module for COVID-19 Monitoring Using IoT

Rapid transmission of the coronavirus disease via droplets and particles has led to a global pandemic. Expeditious detection of SARS-Cov-2 RNA in the environment is attainable by using Bio-FET sensors. This work proposes a Bio-FET sensor interface module with IoT implementation to amplify signals from a Bio-FET for SARS-Cov-2 detection and monitoring. The sensor interface module was programmed to read the signals using a micro-controller and process information to determine the presence of SARS-Cov-2. The proposed Bio-FET sensor interface module was also set to transmit data to the Cloud via W-Fi to be stored and displayed on a dashboard. The prototype Bio-FET sensor interface module was simulated in PSpice for signal amplification, and hardware implementation has been done by using low-cost components for data transmission to the Cloud. The hardware consists of an AD620 instrumentation amplifier module, voltage sensor module, Neo-6m GPS sensor module, an OLED display, and an ESP8266-32 bit micro-controller. The results of both the simulation and the hardware implementation are similar. The emulated negative and positive Bio-FET signal outputs were successfully amplified from 15.9mV and 45.8mV to 1.59V and 4.58V, respectively, using an AD620 instrumentation amplifier. The gathered location, time, date, output voltage, and SARS-Cov-2 presence results were successfully stored and displayed on the Cloud dashboard.

Over Voltage and Under Voltage Protection System Using IoT

Sudden fluctuation in voltage may cause a serious problem in industries and home appliances. These fluctuations may significantly impact the power quality as well as the reliability of other voltage controlling devices. However, this paper discussed about designing for under voltage and over voltage protection to protect and extend the lifespan of home, office and industrial equipments. The AC voltage sensor module ZMPT101B is used in detecting a voltage of -6% of the rated voltage and it is recognized as under voltage while 10% of the rated voltage is recognized as upper voltage. The rated voltage of single phase is normally supply 230 V. Moreover, the sensor is attached with ESP 8266 WiFi platform so that the user can observe the voltage condition through Blynk application. As a conclusion, the combination of voltage protection system through Internet of Thing (IoT) device may contribute to the user.

RANCANG BANGUN PANEL AUTOMATIC TRANSFER SWITCH (ATS) BERBASIS PHOTOVOLTAIC

Automatic Transfer Switch (ATS) is a device that can move the main power source to a backup power source automatically and quickly when the main power source is interrupted or the supply cuts to the load. In this study, ATS was designed based on the Arduino Nano microcontroller as an automatic control that works based on voltage readings. Using the Arduino Nano microcontroller can facilitate the process of making tools and minimize the use of components. This ATS uses the PZEM-004T voltage sensor module. The voltage sensor module functions to detect and measure the value of the PLN voltage. From the test results, it was found that the time lag between the PLN supply being cut off until the battery was supplying and ready to be loaded was an average of 2.79 seconds. Meanwhile, the time lag when the PLN supply turns on again until the battery supply is cut off and the load supply is again served by PLN is 3.07 seconds on average. Other tests found that in measuring battery resistance with a load of 20 watts, the current obtained is 1.66 amperes with a usage resistance of 27 hours, while when the load is 200 watts the current is 16.66 amperes while the resistance to use is 2.7 hours. The length of battery life is affected by the magnitude of the load.

Structural and Functional Characterization of a Novel Scorpion Toxin that Inhibits NaV1.8 via Interactions With the DI Voltage Sensor and DII Pore Module.

Voltage-gated sodium channel NaV1.8 regulates transmission of pain signals to the brain. While NaV1.8 has the potential to serve as a drug target, the molecular mechanisms that shape NaV1.8 gating are not completely understood, particularly mechanisms that couple activation to inactivation. Interactions between toxin producing animals and their predators provide a novel approach for investigating NaV structure-function relationships. Arizona bark scorpions produce Na+ channel toxins that initiate pain signaling. However, in predatory grasshopper mice, toxins inhibit NaV1.8 currents and block pain signals. A screen of synthetic peptide toxins predicted from bark scorpion venom showed that peptide NaTx36 inhibited Na+ current recorded from a recombinant grasshopper mouse NaV1.8 channel (OtNaV1.8). Toxin NaTx36 hyperpolarized OtNaV1.8 activation, steady-state fast inactivation, and slow inactivation. Mutagenesis revealed that the first gating charge in the domain I (DI) S4 voltage sensor and an acidic amino acid (E) in the DII SS2 – S6 pore loop are critical for the inhibitory effects of NaTx36. Computational modeling showed that a DI S1 – S2 asparagine (N) stabilizes the NaTx36 – OtNaV1.8 complex while residues in the DI S3 – S4 linker and S4 voltage sensor form electrostatic interactions that allow a toxin glutamine (Q) to contact the first S4 gating charge. Surprisingly, the models predicted that NaTx36 contacts amino acids in the DII S5 – SS1 pore loop instead of the SS2 – S6 loop; the DII SS2 – S6 loop motif (QVSE) alters the conformation of the DII S5 – SS1 pore loop, enhancing allosteric interactions between toxin and the DII S5 – SS1 pore loop. Few toxins have been identified that modify NaV1.8 gating. Moreover, few toxins have been described that modify sodium channel gating via the DI S4 voltage sensor. Thus, NaTx36 and OtNaV1.8 provide tools for investigating the structure-activity relationship between channel activation and inactivation gating, and the connection to alternative pain phenotypes.

Data Logger berbasis IC Multiplexer untuk Pengukuran Arus dan Tegangan pada Panel Surya Skala Besar

Parameters of large-scale solar panels can be measured directly and automatically using a data logger system. The input data from the data logger can be optimized by using the analog input on the multiplexer IC to improve the performance of recording parameter data on large-scale solar panels. This data logger system consists of an Arduino Uno microcontroller as the central control, which is equipped with a current sensor, voltage sensor, RTC DS3231, multiplexer IC, and SD card module. The data obtained in real-time every 5 minutes will be stored on the SD card in the form of a txt file with the format of the day, date, time, voltage value, and current value on each solar panel. The results of this test will show that the solar panel measurement data using a data logger with multiplexer ICs will be able to store and display large amounts of data on the panel.

Conkunitzin-C2 from Conus consors induces an incomplete block of the Shaker K+ channel using a unique mode of action

Voltage-gated potassium channels (KVs) are activated in response to changes in the electrical membrane potential by coupling a voltage-sensing module with K+ selective pore. Toxins targeting the channel pore can interfere with ion permeation by physically occluding the pore (‘plug mechanism’), by inducing a collapse of the selectivity filter (‘pore-collapse mechanism’), or by trapping the ions in ectopic sites formed at the toxin-channel interface (‘lid mechanism’) to induce a complete channel block.

AUTOMATIC TRANSFER SWITCH UNTUK RUMAH TINGGAL SEDERHANA BERBASIS ARDUINO NANO

Automatic Transfer Switch (ATS) is a device that can move the main power source to a backup power source automatically and quickly when the main power source experiences a disturbance or cut-off of supply to the load. In this study, ATS was designed based on the Arduino Nano microcontroller as an automatic control that works based on voltage readings. Using the Arduino Nano microcontroller can facilitate the process of making tools and minimize the use of components. This ATS uses the PZEM-004T voltage sensor module. The voltage sensor module functions to detect and measure the value of the PLN voltage. From the test results, it was found that the time lag between the PLN supply being cut off until the generator was turned on and ready to load was an average of 2.76 seconds. Meanwhile, the time lag when the PLN supply turns on again until the generator supply is cut off and the load supply is again served by PLN is an average of 1.74 seconds. All working status of this ATS panel can be displayed on the LCD indicator, indicator light and analog voltmeter.

Charge substitutions at the voltage-sensing module of domain III enhance actions of site-3 and site-4 toxins on an insect sodium channel

Scorpion α-toxins bind at the pharmacologically-defined site-3 on the sodium channel and inhibit channel inactivation by preventing the outward movement of the voltage sensor in domain IV (IVS4), whereas scorpion β-toxins bind at site-4 on the sodium channel and enhance channel activation by trapping the voltage sensor of domain II (IIS4) in its outward position. However, limited information is available on the role of the voltage-sensing modules (VSM, comprising S1–S4) of domains I and III in toxin actions. We have previously shown that charge reversing substitutions of the innermost positively-charged residues in IIIS4 (R4E, R5E) increase the activity of an insect-selective site-4 scorpion toxin, Lqh-dprIT3-c, on BgNav1-1a, a cockroach sodium channel. Here we show that substitutions R4E and R5E in IIIS4 also increase the activity of two site-3 toxins, LqhαIT from Leiurusquinquestriatus hebraeus and insect-selective Av3 from Anemonia viridis. Furthermore, charge reversal of either of two conserved negatively-charged residues, D1K and E2K, in IIIS2 also increase the action of the site-3 and site-4 toxins. Homology modeling suggests that S2-D1 and S2-E2 interact with S4-R4 and S4-R5 in the VSM of domain III (III-VSM), respectively, in the activated state of the channel. However, charge swapping between S2-D1 and S4-R4 had no compensatory effects on gating or toxin actions, suggesting that charged residue interactions are complex. Collectively, our results highlight the involvement of III-VSM in the actions of both site 3 and site 4 toxins, suggesting that charge reversing substitutions in III-VSM allosterically facilitate IIS4 or IVS4 voltage sensor trapping by these toxins.

Prospective Powering Strategy Development for Intelligent-Tire Sensor Power Charger Application

Tire sensors embedded in a vehicle tire are stand-alone autonomous devices. A tire sensor reserve power strategy is crucial due to sensor energy sources limitations for long operational periods. This paper presents an innovative tire sensor powering strategy for the intelligent-tire system. The powering strategy offers a green concept, maintenance-free, and low-cost method in order to extend the tire sensor lifetime for long operating periods. The proposed strategy adopts wireless power transfer (WPT) technology to transfer power to an electrical load mounted on the rotational system without an interconnection cable. It is composed of a power transmitter designed to be mounted on the vehicle’s inner fender liner, and a power receiver that provides power to recharge the tire sensor battery/energy storage. The transmitter transfers power from the vehicle battery/accumulator to a power receiver coupled with the tire sensor which is mounted on the vehicle tire inner wall. WPT devices were designed based on induction electromagnetic coupling and can provide an output current up to 1A at 5 V. The proposed powering strategy was verified using a vehicle tire simulator model to emulate rotational motion. A voltage and current sensor module as well microcontroller and data logger modules were utilized as the load for the developed WPT system. The verification experimental and preliminary test results reveal that the proposed strategy can provide constant power to the load (in this case, the voltage is around 4.3 V and the current is around 21.1 mA) although the vehicle tire model was rotated at different speeds from 0 rpm to 800 rpm. The proposed system has the potential and feasibility for implementation in tire sensor power applications in the intelligent-tire system.

Cysteine Mutagenesis to Probe Site-Specific Interactions in the Voltage Sensor Module of hNaV1.4

Cysteine scanning mutagenesis was used to probe interactions of positively charged S4 residues with S1-S3 countercharges in domains I, II and IV of the human skeletal muscle sodium channel hNaV1.4. Single cysteine substitution was used to assess the effect of charge neutralization of residues in the voltage sensor module of these domains. Activation and fast inactivation were most affected by cysteine substitution in domains II and IV respectively, while both of these state transitions were affected by like mutations in domain I. Double cysteine mutations in the VSM of each of these domains did not result in disulfide locking. To probe for specific interactions using these mutations, we employed a metal ion bridge approach using cadmium, and assessed its effect on equilibrium parameters of activation and fast inactivation, and peak current amplitude. In domain I, double cysteine mutations of R219C or R222C with the gating charge transfer glutamate (E171C) significantly affected fast inactivation, with activation midpoint significantly depolarized by several DIS4 cysteine / countercharge mutations incorporating the polar residue substitutions N144C and S134C. Domain II double cysteine mutations R672C / E598C and R675C / E598C also significantly depolarized the activation midpoint with cadmium addition. In domain IV, double cysteine mutations R1448C / E1373C and R1448C / N1389C responded to cadmium with slowed entry into fast inactivation, a depolarized inactivation midpoint and a decreased slope. Our results show that certain domain specific functions of the voltage sensor modules in hNaV1.4 occur with pairwise interactions of S4 positive and S1-S3 countercharge residues. This work was supported by NIH R15NS093579-01A1 to JRG and NIH P20GM103408 (INBRE).

Pore-modulating toxins exploit inherent slow inactivation to block K+ channels

Voltage-dependent potassium channels (Kvs) gate in response to changes in electrical membrane potential by coupling a voltage-sensing module with a K+-selective pore. Animal toxins targeting Kvs are classified as pore blockers, which physically plug the ion conduction pathway, or as gating modifiers, which disrupt voltage sensor movements. A third group of toxins blocks K+ conduction by an unknown mechanism via binding to the channel turrets. Here, we show that Conkunitzin-S1 (Cs1), a peptide toxin isolated from cone snail venom, binds at the turrets of Kv1.2 and targets a network of hydrogen bonds that govern water access to the peripheral cavities that surround the central pore. The resulting ectopic water flow triggers an asymmetric collapse of the pore by a process resembling that of inherent slow inactivation. Pore modulation by animal toxins exposes the peripheral cavity of K+ channels as a novel pharmacological target and provides a rational framework for drug design.

Inhibition of the K+ conductance and Cole-Moore shift of the oncogenic Kv10.1 channel by amiodarone.

The ectopic overexpression of the voltage-dependent Eag1 (Kv10.1) K+ channel is associated with the cancerous phenotype in about 70% of human cancers and tumor cell lines. Recent reports showed that, compared with the canonical Shaker-related Kv family, Kv10.1 presents unique structural and functional properties. Herein, we report the interaction of the class III anti-arrhythmic compound amiodarone with Kv10.1. Using whole-cell patch clamp, we found that amiodarone inhibits Kv10.1 channel conductance with nanomolar affinity. Additionally, and interestingly, we also report that amiodarone inhibits the characteristic Cole-Moore shift of Eag1 channels. Our observations are interpreted considering the structural-functional characteristics of these channels. We conclude that amiodarone possibly binds with high affinity to the voltage sensor module, altering the gating of Kv10.1.

A novel tarantula toxin stabilizes the deactivated voltage sensor of bacterial sodium channel.

Voltage-gated sodium channels (NaVs) are activated by transiting the voltage sensor from the deactivated to the activated state. The crystal structures of several bacterial NaVs have captured the voltage sensor module (VSM) in an activated state, but structure of the deactivated voltage sensor remains elusive. In this study, we sought to identify peptide toxins stabilizing the deactivated VSM of bacterial NaVs. We screened fractions from several venoms and characterized a cystine knot toxin called JZTx-27 from the venom of tarantula Chilobrachys jingzhao as a high-affinity antagonist of the prokaryotic NaVs NsVBa (nonselective voltage-gated Bacillus alcalophilus) and NaChBac (bacterial sodium channel from Bacillus halodurans) (IC50 = 112 nM and 30 nM, respectively). JZTx-27 was more efficacious at weaker depolarizing voltages and significantly slowed the activation but accelerated the deactivation of NsVBa, whereas the local anesthetic drug lidocaine was shown to antagonize NsVBa without affecting channel gating. Mutation analysis confirmed that JZTx-27 bound to S3-4 linker of NsVBa, with F98 being the critical residue in determining toxin affinity. All electrophysiological data and in silico analysis suggested that JZTx-27 trapped VSM of NsVBa in one of the deactivated states. In mammalian NaVs, JZTx-27 preferably inhibited the inactivation of NaV1.5 by targeting the fourth transmembrane domain. To our knowledge, this is the first report of peptide antagonist for prokaryotic NaVs. More important, we proposed that JZTx-27 stabilized the NsVBa VSM in the deactivated state and may be used as a probe to determine the structure of the deactivated VSM of NaVs.-Tang, C., Zhou, X., Nguyen, P. T., Zhang, Y., Hu, Z., Zhang, C., Yarov-Yarovoy, V., DeCaen, P. G., Liang, S., Liu, Z. A novel tarantula toxin stabilizes the deactivated voltage sensor of bacterial sodium channel.

Molecular pathophysiology and pharmacology of the voltage-sensing module of neuronal ion channels.

Voltage-gated ion channels (VGICs) are membrane proteins that switch from a closed to open state in response to changes in membrane potential, thus enabling ion fluxes across the cell membranes. The mechanism that regulate the structural rearrangements occurring in VGICs in response to changes in membrane potential still remains one of the most challenging topic of modern biophysics. Na+, Ca2+ and K+ voltage-gated channels are structurally formed by the assembly of four similar domains, each comprising six transmembrane segments. Each domain can be divided into two main regions: the Pore Module (PM) and the Voltage-Sensing Module (VSM). The PM (helices S5 and S6 and intervening linker) is responsible for gate opening and ion selectivity; by contrast, the VSM, comprising the first four transmembrane helices (S1–S4), undergoes the first conformational changes in response to membrane voltage variations. In particular, the S4 segment of each domain, which contains several positively charged residues interspersed with hydrophobic amino acids, is located within the membrane electric field and plays an essential role in voltage sensing. In neurons, specific gating properties of each channel subtype underlie a variety of biological events, ranging from the generation and propagation of electrical impulses, to the secretion of neurotransmitters and to the regulation of gene expression. Given the important functional role played by the VSM in neuronal VGICs, it is not surprising that various VSM mutations affecting the gating process of these channels are responsible for human diseases, and that compounds acting on the VSM have emerged as important investigational tools with great therapeutic potential. In the present review we will briefly describe the most recent discoveries concerning how the VSM exerts its function, how genetically inherited diseases caused by mutations occurring in the VSM affects gating in VGICs, and how several classes of drugs and toxins selectively target the VSM.

Discontinuity between the Voltage-Sensor and the Pore Domain does not Abolish Voltage-Gating of Kv10.1 Potassium Channel

Voltage-gating of ion channels is crucial for excitable tissues, such as nerve and muscle. Here we show that a voltage-gated potassium channel retains its voltage-dependency of activation, even when the voltage sensor and the pore domain are expressed as two individual proteins from separate cRNAs in Xenopus laevis oocytes. Not only interrupting the S4-S5 cytoplasmic linker at various positions, but also concomitant deletion of several consecutive amino acids from this region yielded functional channels. Moreover, mutations of the voltage-sensor that shift the conductance-voltage curve in either hyperpolarizing or depolarizing direction cause the same shift when the S4-S5 linker is disrupted. Detailed characterization of how the location of discontinuity affects the voltage and time-dependence of activation and deactivation of the split constructs sheds new light on the coupling between the voltage-sensing module and the channel gate.Our findings indicate that an intact S4-S5 linker is not a sine qua non condition for voltage gating in Kv10.1. In consequence, the idea of direct mechanical coupling between the voltage sensor and the pore mediated by the S4-S5 linker needs to be revised, at least for the KNCH-family channels, which may have a different gating mechanism than Shaker.

Mapping the interaction site for the tarantula toxin hainantoxin-IV (β-TRTX-Hn2a) in the voltage sensor module of domain II of voltage-gated sodium channels

Peptide toxins often have pharmacological applications and are powerful tools for investigating the structure–function relationships of voltage-gated sodium channels (VGSCs). Although a group of potential VGSC inhibitors have been reported from tarantula venoms, little is known about the mechanism of their interaction with VGSCs. In this study, we showed that hainantoxin-IV (β-TRTX-Hn2a, HNTX-IV in brief), a 35-residue peptide from Ornithoctonus hainana venom, preferentially inhibited rNav1.2, rNav1.3 and hNav1.7 compared with rNav1.4 and hNav1.5. hNav1.7 was the most sensitive to HNTX-IV (IC50∼21nM). In contrast to many other tarantula toxins that affect VGSCs, HNTX-IV at subsaturating concentrations did not alter activation and inactivation kinetics in the physiological range of voltages, while very large depolarization above +70mV could partially activate toxin-bound hNav1.7 channel, indicating that HNTX-IV acts as a gating modifier rather than a pore blocker. Site-directed mutagenesis indicated that the toxin bound to site 4, which was located on the extracellular S3–S4 linker of hNav1.7 domain II. Mutants E753Q, D816N and E818Q of hNav1.7 decreased toxin affinity for hNav1.7 by 2.0-, 3.3- and 130-fold, respectively. In silico docking indicated that a three-toed claw substructure formed by residues with close contacts in the interface between HNTX-IV and hNav1.7 domain II stabilized the toxin–channel complex, impeding movement of the domain II voltage sensor and inhibiting hNav1.7 activation. Our data provide structural details for structure-based drug design and a useful template for the design of highly selective inhibitors of a specific subtype of VGSCs.

Domain III S4 in closed-state fast inactivation: Insights from a periodic paralysis mutation

Heterologous expression of sodium channel mutations in hypokalemic periodic paralysis reveals 2 variants on channel dysfunction. Charge-reducing mutations of voltage sensing S4 arginine residues alter channel gating as typically studied with expression in mammalian cells. These mutations also produce leak currents through the voltage sensor module, as typically studied with expression in Xenopus oocytes. DIIIS4 mutations at R3 in the skeletal muscle sodium channel produce gating defects and omega current consistent with the phenotype of reduced excitability. Here, we confirm DIIIS4 R3C gating defects in the oocyte expression system for fast inactivation and its recovery. We provide novel data for the effects of the cysteine mutation on voltage sensor movement, to further our understanding of sodium channel defects in hypokalemic periodic paralysis. Gating charge movement and its remobilization are selectively altered by the mutation at hyperpolarized membrane potential, as expected with reduced serum potassium.

NaV1.4 mutations cause hypokalaemic periodic paralysis by disrupting IIIS4 movement during recovery

Hypokalaemic periodic paralysis is typically associated with mutations of voltage sensor residues in calcium or sodium channels of skeletal muscle. To date, causative sodium channel mutations have been studied only for the two outermost arginine residues in S4 voltage sensor segments of domains I to III. These mutations produce depolarization of skeletal muscle fibres in response to reduced extracellular potassium, owing to an inward cation-selective gating pore current activated by hyperpolarization. Here, we describe mutations of the third arginine, R3, in the domain III voltage sensor i.e. an R1135H mutation which was found in two patients in separate families and a novel R1135C mutation identified in a third patient in another family. Muscle fibres from a patient harbouring the R1135H mutation showed increased depolarization tendency at normal and reduced extracellular potassium compatible with the diagnosis. Additionally, amplitude and rise time of action potentials were reduced compared with controls, even for holding potentials at which all NaV1.4 are fully recovered from inactivation. These findings may be because of an outward omega current activated at positive potentials. Expression of R1135H/C in mammalian cells indicates further gating defects that include significantly enhanced entry into inactivation and prolonged recovery that may additionally contribute to action potential inhibition at the physiological resting potential. After S4 immobilization in the outward position, mutant channels produce an inward omega current that most likely depolarizes the resting potential and produces the hypokalaemia-induced weakness. Gating current recordings reveal that mutations at R3 inhibit S4 deactivation before recovery, and molecular dynamics simulations suggest that this defect is caused by disrupted interactions of domain III S2 countercharges with S4 arginines R2 to R4 during repolarization of the membrane. This work reveals a novel mechanism of disrupted S4 translocation for hypokalaemic periodic paralysis mutations at arginine residues located below the gating pore constriction of the voltage sensor module.

Biology of the KCNQ1 Potassium Channel

Ion channels are essential for basic cellular function and for processes including sensory perception and intercellular communication in multicellular organisms. Voltage-gated potassium (Kv) channels facilitate dynamic cellular repolarization during an action potential, opening in response to membrane depolarization to facilitate K+efflux. In both excitable and nonexcitable cells other, constitutively active, K+channels provide a relatively constant repolarizing force to control membrane potential, ion homeostasis, and secretory processes. Of the forty known human Kv channel pore-formingαsubunits that coassemble in various combinations to form the fundamental tetrameric channel pore and voltage sensor module, KCNQ1 is unique. KCNQ1 stands alone in having the capacity to form either channels that are voltage-dependent and require membrane depolarization for activation, or constitutively active channels. In mammals, KCNQ1 regulates processes including gastric acid secretion, thyroid hormone biosynthesis, salt and glucose homeostasis, and cell volume and in some species is required for rhythmic beating of the heart. In this review, the author discusses the unique functional properties, regulation, cell biology, diverse physiological roles, and involvement in human disease states of this chameleonic K+channel.