Physical model of voltage sensing in sodium channels based on the sliding helix complex

Scorpion β-toxins bind to the extracellular regions of the voltage-sensing module of domain II and to the pore module of domain III in voltage-gated sodium channels and enhance channel activation by trapping and stabilizing the voltage sensor of domain II in its activated state. We investigated the interaction of a highly potent insect-selective scorpion depressant β-toxin, Lqh-dprIT3, from Leiurus quinquestriatus hebraeus with insect sodium channels from Blattella germanica (BgNav). Like other scorpion β-toxins, Lqh-dprIT3 shifts the voltage dependence of activation of BgNav channels expressed in Xenopus oocytes to more negative membrane potentials but only after strong depolarizing prepulses. Notably, among 10 BgNav splice variants tested for their sensitivity to the toxin, only BgNav1-1 was hypersensitive due to an L1285P substitution in IIIS1 resulting from a U-to-C RNA-editing event. Furthermore, charge reversal of a negatively charged residue (E1290K) at the extracellular end of IIIS1 and the two innermost positively charged residues (R4E and R5E) in IIIS4 also increased the channel sensitivity to Lqh-dprIT3. Besides enhancement of toxin sensitivity, the R4E substitution caused an additional 20-mV negative shift in the voltage dependence of activation of toxin-modified channels, inducing a unique toxin-modified state. Our findings provide the first direct evidence for the involvement of the domain III voltage-sensing module in the action of scorpion β-toxins. This hypersensitivity most likely reflects an increase in IIS4 trapping via allosteric mechanisms, suggesting coupling between the voltage sensors in neighboring domains during channel activation.

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Searching for the Interaction Sites of the Beta1 Subunit with the Voltage-Sensing Domains of Sodium Channels Using LRET

Biophysical Journal ◽

10.1016/j.bpj.2013.11.780 ◽

2014 ◽

Vol 106 (2) ◽

pp. 133a

Author(s):

Tomoya Kubota ◽

Bobo Dang ◽

Rocio K. Finol-Urdaneta ◽

Jérôme J. Lacroix ◽

Ludivine Frezza ◽

...

Keyword(s):

Sodium Channels ◽

Voltage Sensing ◽

Interaction Sites ◽

Beta1 Subunit

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Neuronal Sodium Channels in Neurodegeneration and Neuroprotection

PsycEXTRA Dataset ◽

10.1037/e452222006-001 ◽

2003 ◽

Author(s):

Frank C. Tortella ◽

Keyword(s):

Sodium Channels

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Medullary epithelial sodium channels (ENAC) participate in cerebral blood flow (CBF) autoregulation

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/sj.jcbfm.9591524.0190 ◽

2005 ◽

Vol 25 (1_suppl) ◽

pp. S190-S190

Author(s):

Eugene Golanov ◽

Heather Drummond ◽

Jasleen Shant ◽

Benjamin Clower ◽

Betty Chen

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Sodium Channels ◽

Epithelial Sodium Channels

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EXPERIMENTAL STUDIES OF CAR PROPERTIES ON A PHYSICAL MODEL

Avtoshliakhovyk Ukrayiny ◽

10.33868/0365-8392-2019-4-260-10-16 ◽

2019 ◽

pp. 10-16

Author(s):

Oleksii Timkov ◽

Dmytro Yashchenko ◽

Volodymyr Bosenko

Keyword(s):

Mathematical Model ◽

Remote Control ◽

Physical Model ◽

Model Experiment ◽

Experimental Studies ◽

Electrical Energy ◽

Short Term ◽

Motor Current ◽

Memory Card ◽

The Mathematical Model

The article deals with the development of a physical model of a car equipped with measuring, recording and remote control equipment for experimental study of car properties. A detailed description of the design of the physical model and of the electronic modules used is given, links to application libraries and the code of the first part of the program for remote control of the model are given. Atmega microcontroller on the Arduino Uno platform was used to manage the model and register the parameters. When moving the car on the memory card saved such parameters as speed, voltage on the motor, current on the motor, the angle of the steered wheel, acceleration along three coordinate axes are recorded. Use of more powerful microcontrollers will allow to expand the list of the registered parameters of movement of the car. It is possible to measure the forces acting on the elements of the car and other parameters. In the future, it is planned to develop a mathematical model of motion of the car and check its adequacy in conducting experimental studies on maneuverability on the physical model. In addition, it is possible to conduct studies of stability and consumption of electrical energy. The physical model allows to quickly change geometric dimensions and mass parameters. In the study of highway trains, this approach will allow to investigate the various layout schemes of highway trains in the short term. It is possible to make two-axle road trains and saddle towed trains, three-way hitched trains of different layout. The results obtained will allow us to improve not only the mathematical model, but also the experimental physical model, and move on to further study the properties of hybrid road trains with an active trailer link. This approach allows to reduce material and time costs when researching the properties of cars and road trains. Keywords: car, physical model, experiment, road trains, sensor, remote control, maneuverability, stability.

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