scholarly journals Modeling the Interactions Between Sodium Channels Provides Insight Into the Negative Dominance of Certain Channel Mutations

2020 ◽  
Vol 11 ◽  
Author(s):  
Echrak Hichri ◽  
Zoja Selimi ◽  
Jan P. Kucera
Keyword(s):  
Sodium Channels ◽  
Negative Dominance ◽  
Insight Into

Intrinsic gating mechanisms of epithelial sodium channels

2002 ◽  
Vol 283 (2) ◽  
pp. C646-C650 ◽  
Author(s):  
Hong-Long Ji ◽  
Catherine M. Fuller ◽  
Dale J. Benos
Keyword(s):  
Sodium Channels ◽  
Xenopus Oocytes ◽  
Transmembrane Domain ◽  
Receptor Site ◽  
Epithelial Sodium Channels ◽  
Gating Mechanisms ◽  
Putative Receptor ◽  
Arginine Residues ◽  
Insight Into ◽  
Positively Charged

The hypothesis that there is a highly conserved, positively charged region distal to the second transmembrane domain in α-ENaC (epithelial sodium channel) that acts as a putative receptor site for the negatively charged COOH-terminal β- and γ-ENaC tails was tested in mutagenesis experiments. After expression in Xenopus oocytes, α-ENaC constructs in which positively charged arginine residues were converted into negatively charged glutamic acids could not be inhibited by blocking peptides. These observations provide insight into the gating machinery of ENaC.

scholarly journals FGF14 is a regulator of KCNQ2/3 channels

2016 ◽  
Vol 114 (1) ◽  
pp. 154-159 ◽  
Author(s):  
Juan Lorenzo Pablo ◽  
Geoffrey S. Pitt
Keyword(s):  
Membrane Potential ◽  
Sodium Channels ◽  
Molecular Mechanisms ◽  
Expression System ◽  
Cellular Mechanisms ◽  
Ankyrin G ◽  
Voltage Gated Sodium Channels ◽  
A Site ◽  
Interaction Surface ◽  
Insight Into

KCNQ2/3 (Kv7.2/7.3) channels and voltage-gated sodium channels (VGSCs) are enriched in the axon initial segment (AIS) where they bind to ankyrin-G and coregulate membrane potential in central nervous system neurons. The molecular mechanisms supporting coordinated regulation of KCNQ and VGSCs and the cellular mechanisms governing KCNQ trafficking to the AIS are incompletely understood. Here, we show that fibroblast growth factor 14 (FGF14), previously described as a VGSC regulator, also affects KCNQ function and localization. FGF14 knockdown leads to a reduction of KCNQ2 in the AIS and a reduction in whole-cell KCNQ currents. FGF14 positively regulates KCNQ2/3 channels in a simplified expression system. FGF14 interacts with KCNQ2 at a site distinct from the FGF14–VGSC interaction surface, thus enabling the bridging of NaV1.6 and KCNQ2. These data implicate FGF14 as an organizer of channel localization in the AIS and provide insight into the coordination of KCNQ and VGSC conductances in the regulation of membrane potential.

Cloning of a putative voltage-gated sodium channel from the turbellarian flatworm Bdelloura candida

Parasitology ◽  
1997 ◽  
Vol 115 (3) ◽  
pp. 289-296 ◽  
Author(s):  
M. C. JEZIORSKI ◽  
R. M. GREENBERG ◽  
P. A. V. ANDERSON
Keyword(s):  
Sodium Channels ◽  
Northern Blot Analysis ◽  
Amino Acid Identity ◽  
Structure Characteristic ◽  
Sodium Currents ◽  
Voltage Gated ◽  
Transmembrane Segments ◽  
Voltage Gated Sodium Channels ◽  
Multidomain Structure ◽  
Insight Into

The neuromuscular sodium currents of early invertebrates such as platyhelminths display distinctive kinetic and pharmacological properties. We have cloned a cDNA from the horseshoe crab flatworm Bdelloura candida that encodes a protein homologous to the primary subunit of voltage-gated sodium channels. The B. candida protein, named BdNa1, exhibits amino acid identity of 40–47% to sodium channels of vertebrates and higher invertebrates. BdNa1 has the multidomain structure characteristic of sodium channels, and is most highly conserved in the hydrophobic transmembrane segments and the regions that form the pore of the channel. Northern blot analysis confirms the presence of a 5·4 kb BdNa1 transcript in B. candida tissue. The information provided by analysis of the BdNa1 sequence offers insight into the physiology of platyhelminth sodium currents.

Calibration problems in hydrogen luminosities

1966 ◽  
Vol 24 ◽  
pp. 322-330
Author(s):  
A. Beer
Keyword(s):  
Galactic Structure ◽  
B Stars ◽  
Insight Into

The investigations which I should like to summarize in this paper concern recent photo-electric luminosity determinations of O and B stars. Their final aim has been the derivation of new stellar distances, and some insight into certain patterns of galactic structure.

Stochasting modeling of planetary ring systems

1984 ◽  
Vol 75 ◽  
pp. 461-469 ◽  
Author(s):  
Robert W. Hart
Keyword(s):  
Maximum Entropy ◽  
Ring System ◽  
The Sun ◽  
Ultimate State ◽  
Interparticle Interactions ◽  
Ring Systems ◽  
First Order ◽  
Planetary Ring ◽  
Insight Into

ABSTRACTThis paper models maximum entropy configurations of idealized gravitational ring systems. Such configurations are of interest because systems generally evolve toward an ultimate state of maximum randomness. For simplicity, attention is confined to ultimate states for which interparticle interactions are no longer of first order importance. The planets, in their orbits about the sun, are one example of such a ring system. The extent to which the present approximation yields insight into ring systems such as Saturn's is explored briefly.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Structure and function of neural networks in the retina

1988 ◽  
Vol 46 ◽  
pp. 26-27
Author(s):  
Peter Sterling
Keyword(s):  
Ganglion Cells ◽  
Three Dimensional ◽  
Structure And Function ◽  
Synaptic Connections ◽  
Visual Axis ◽  
One Dimensional ◽  
Cat Retina ◽  
Ultrathin Sections ◽  
And Function ◽  
Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

Radiation Damage Studies with the HVEM

1972 ◽  
Vol 30 ◽  
pp. 680-681
Author(s):  
J. J. Laidler ◽  
B. Mastel
Keyword(s):  
Radiation Damage ◽  
Stainless Steels ◽  
Volume Expansion ◽  
Austenitic Stainless Steels ◽  
Test Facility ◽  
Fast Breeder Reactors ◽  
Breeder Reactors ◽  
Under Construction ◽  
Development Laboratory ◽  
Insight Into

One of the major materials problems encountered in the development of fast breeder reactors for commercial power generation is the phenomenon of swelling in core structural components and fuel cladding. This volume expansion, which is due to the retention of lattice vacancies by agglomeration into large polyhedral clusters (voids), may amount to ten percent or greater at goal fluences in some austenitic stainless steels. From a design standpoint, this is an undesirable situation, and it is necessary to obtain experimental confirmation that such excessive volume expansion will not occur in materials selected for core applications in the Fast Flux Test Facility, the prototypic LMFBR now under construction at the Hanford Engineering Development Laboratory (HEDL). The HEDL JEM-1000 1 MeV electron microscope is being used to provide an insight into trends of radiation damage accumulation in stainless steels, since it is possible to produce atom displacements at an accelerated rate with 1 MeV electrons, while the specimen is under continuous observation.

Failure Analysis With the Scanning Electron Microscope

1972 ◽  
Vol 30 ◽  
pp. 482-483
Author(s):  
John R. Devaney
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Integrated Circuits ◽  
Failure Analysis ◽  
High Reliability ◽  
Military Applications ◽  
Small Structure ◽  
Useful Life ◽  
Insight Into ◽  
Scanning Electron

Occasionally in history, an event may occur which has a profound influence on a technology. Such an event occurred when the scanning electron microscope became commercially available to industry in the mid 60's. Semiconductors were being increasingly used in high-reliability space and military applications both because of their small volume but, also, because of their inherent reliability. However, they did fail, both early in life and sometimes in middle or old age. Why they failed and how to prevent failure or prolong “useful life” was a worry which resulted in a blossoming of sophisticated failure analysis laboratories across the country. By 1966, the ability to build small structure integrated circuits was forging well ahead of techniques available to dissect and analyze these same failures. The arrival of the scanning electron microscope gave these analysts a new insight into failure mechanisms.

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