scholarly journals Non-linear intramolecular interactions and voltage sensitivity of a KV1 family potassium channel from Polyorchis penicillatus (Eschscholtz 1829)

2008 ◽  
Vol 211 (21) ◽  
pp. 3442-3453 ◽  
Author(s):  
T. L. Klassen ◽  
M. L. O'Mara ◽  
M. Redstone ◽  
A. N. Spencer ◽  
W. J. Gallin
Keyword(s):  
Potassium Channel ◽  
Intramolecular Interactions ◽  
Voltage Sensitivity ◽  
Polyorchis Penicillatus ◽  
Non Linear

scholarly journals A Theoretical Model for Calculating Voltage Sensitivity of Ion Channels and the Application on Kv1.2 Potassium Channel

2012 ◽  
Vol 102 (8) ◽  
pp. 1815-1825 ◽  
Author(s):  
Huaiyu Yang ◽  
Zhaobing Gao ◽  
Ping Li ◽  
Kunqian Yu ◽  
Ye Yu ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Ion Channels ◽  
Potassium Channel ◽  
Voltage Sensitivity

scholarly journals Voltage-dependent gating and gating charge measurements in the Kv1.2 potassium channel

2015 ◽  
Vol 145 (4) ◽  
pp. 345-358 ◽  
Author(s):  
Itzel G. Ishida ◽  
Gisela E. Rangel-Yescas ◽  
Julia Carrasco-Zanini ◽  
León D. Islas
Keyword(s):  
Ion Channels ◽  
Potassium Channel ◽  
Structural Data ◽  
Activation Mechanism ◽  
Voltage Sensitivity ◽  
Structural Interpretation ◽  
Kv Channel ◽  
Gating Charge ◽  
Voltage Dependent ◽  
Electrophysiological Findings

Much has been learned about the voltage sensors of ion channels since the x-ray structure of the mammalian voltage-gated potassium channel Kv1.2 was published in 2005. High resolution structural data of a Kv channel enabled the structural interpretation of numerous electrophysiological findings collected in various ion channels, most notably Shaker, and permitted the development of meticulous computational simulations of the activation mechanism. The fundamental premise for the structural interpretation of functional measurements from Shaker is that this channel and Kv1.2 have the same characteristics, such that correlation of data from both channels would be a trivial task. We tested these assumptions by measuring Kv1.2 voltage-dependent gating and charge per channel. We found that the Kv1.2 gating charge is near 10 elementary charges (eo), ∼25% less than the well-established 13–14 eo in Shaker. Next, we neutralized positive residues in the Kv1.2 S4 transmembrane segment to investigate the cause of the reduction of the gating charge and found that, whereas replacing R1 with glutamine decreased voltage sensitivity to ∼50% of the wild-type channel value, mutation of the subsequent arginines had a much smaller effect. These data are in marked contrast to the effects of charge neutralization in Shaker, where removal of the first four basic residues reduces the gating charge by roughly the same amount. In light of these differences, we propose that the voltage-sensing domains (VSDs) of Kv1.2 and Shaker might undergo the same physical movement, but the septum that separates the aqueous crevices in the VSD of Kv1.2 might be thicker than Shaker’s, accounting for the smaller Kv1.2 gating charge.

scholarly journals Designer and natural peptide toxin blockers of the KcsA potassium channel identified by phage display

2015 ◽  
Vol 112 (50) ◽  
pp. E7013-E7021 ◽  
Author(s):  
Ruiming Zhao ◽  
Hui Dai ◽  
Netanel Mendelman ◽  
Luis G. Cuello ◽  
Jordan H. Chill ◽  
...  
Keyword(s):  
Phage Display ◽  
Potassium Channel ◽  
Lipid Bilayers ◽  
Disulfide Bonds ◽  
3D Structure ◽  
Structural Basis ◽  
Voltage Sensitivity ◽  
Type I ◽  
High Affinity ◽  
Kv1.3 Channels

Peptide neurotoxins are powerful tools for research, diagnosis, and treatment of disease. Limiting broader use, most receptors lack an identified toxin that binds with high affinity and specificity. This paper describes isolation of toxins for one such orphan target, KcsA, a potassium channel that has been fundamental to delineating the structural basis for ion channel function. A phage-display strategy is presented whereby ∼1.5 million novel and natural peptides are fabricated on the scaffold present in ShK, a sea anemone type I (SAK1) toxin stabilized by three disulfide bonds. We describe two toxins selected by sorting on purified KcsA, one novel (Hui1, 34 residues) and one natural (HmK, 35 residues). Hui1 is potent, blocking single KcsA channels in planar lipid bilayers half-maximally (Ki) at 1 nM. Hui1 is also specific, inhibiting KcsA-Shaker channels in Xenopus oocytes with a Ki of 0.5 nM whereas Shaker, Kv1.2, and Kv1.3 channels are blocked over 200-fold less well. HmK is potent but promiscuous, blocking KcsA-Shaker, Shaker, Kv1.2, and Kv1.3 channels with Ki of 1–4 nM. As anticipated, one Hui1 blocks the KcsA pore and two conserved toxin residues, Lys21 and Tyr22, are essential for high-affinity binding. Unexpectedly, potassium ions traversing the channel from the inside confer voltage sensitivity to the Hui1 off-rate via Arg23, indicating that Lys21 is not in the pore. The 3D structure of Hui1 reveals a SAK1 fold, rationalizes KcsA inhibition, and validates the scaffold-based approach for isolation of high-affinity toxins for orphan receptors.

scholarly journals Fine-tuning of Voltage Sensitivity of the Kv1.2 Potassium Channel by Interhelix Loop Dynamics

2013 ◽  
Vol 288 (14) ◽  
pp. 9686-9695 ◽  
Author(s):  
Rheanna Sand ◽  
Nazlee Sharmin ◽  
Carla Morgan ◽  
Warren J. Gallin
Keyword(s):  
Potassium Channel ◽  
Fine Tuning ◽  
Voltage Sensitivity ◽  
Loop Dynamics

B. The Non-Linear Calculations for Pulsating Stars

1967 ◽  
Vol 28 ◽  
pp. 105-176
Author(s):  
Robert F. Christy
Keyword(s):  
Major Part ◽  
Afternoon Session ◽  
Discussion Session ◽  
Pulsating Stars ◽  
Fourth Symposium ◽  
Non Linear ◽  
Considerable Discussion ◽  
Informal Approach ◽  
Preceding Session

(Ed. note: The custom in these Symposia has been to have a summary-introductory presentation which lasts about 1 to 1.5 hours, during which discussion from the floor is minor and usually directed at technical clarification. The remainder of the session is then devoted to discussion of the whole subject, oriented around the summary-introduction. The preceding session, I-A, at Nice, followed this pattern. Christy suggested that we might experiment in his presentation with a much more informal approach, allowing considerable discussion of the points raised in the summary-introduction during its presentation, with perhaps the entire morning spent in this way, reserving the afternoon session for discussion only. At Varenna, in the Fourth Symposium, several of the summaryintroductory papers presented from the astronomical viewpoint had been so full of concepts unfamiliar to a number of the aerodynamicists-physicists present, that a major part of the following discussion session had been devoted to simply clarifying concepts and then repeating a considerable amount of what had been summarized. So, always looking for alternatives which help to increase the understanding between the different disciplines by introducing clarification of concept as expeditiously as possible, we tried Christy's suggestion. Thus you will find the pattern of the following different from that in session I-A. I am much indebted to Christy for extensive collaboration in editing the resulting combined presentation and discussion. As always, however, I have taken upon myself the responsibility for the final editing, and so all shortcomings are on my head.)

A decomposition method in non-linear programmm

Optimization ◽  
1975 ◽  
Vol 6 (4) ◽  
pp. 549-559
Author(s):  
L. Gerencsér
Keyword(s):  
Decomposition Method ◽  
Non Linear
Sign in / Sign up

Export Citation Format

Share Document