Bufo marinus Oocytes as a Model for Ion Channel Protein Expression and Functional Characterization for Electrophysiological Studies

2004 ◽  
Vol 14 (4-6) ◽  
pp. 197-202 ◽  
Author(s):  
Rafael Vargas ◽  
Lucía Botero ◽  
Luisa Lagos ◽  
Marcela Camacho
Keyword(s):  
Protein Expression ◽  
Ion Channel ◽  
Functional Characterization ◽  
Bufo Marinus ◽  
Channel Protein ◽  
Electrophysiological Studies

scholarly journals Definitive Assignment of Proton Selectivity and Attoampere Unitary Current to the M2 Ion Channel Protein of Influenza A Virus

2001 ◽  
Vol 75 (8) ◽  
pp. 3647-3656 ◽  
Author(s):  
Tse-I Lin ◽  
Cornelia Schroeder
Keyword(s):  
Influenza Virus ◽  
Ion Channel ◽  
Metal Ion ◽  
Influenza A ◽  
Ion Selectivity ◽  
Single Channels ◽  
Channel Protein ◽  
Channel Current ◽  
Viral Hemagglutinin ◽  
Electrophysiological Studies

ABSTRACT The viral ion channel protein M2 supports the transit of influenza virus and its glycoproteins through acidic compartments of the cell. M2 conducts endosomal protons into the virion to initiate uncoating and, by equilibrating the pH at trans-Golgi membranes, preserves the native conformation of acid-sensitive viral hemagglutinin. The exceptionally low conductance of the M2 channel thwarted resolution of single channels by electrophysiological techniques. Assays of liposome-reconstituted M2 yielded the average unitary channel current of the M2 tetramer—1.2 aA (1.2 × 10−18 A) at neutral pH and 2.7 to 4.1 aA at pH 5.7—which activates the channel. Extrapolation to physiological temperature predicts 4.8 and 40 aA, respectively, and a unitary conductance of 0.03 versus 0.4 fS. This minute activity, below previous estimates, appears sufficient for virus reproduction, but low enough to avert abortive cytotoxicity. The unitary permeability of M2 was within the range reported for other proton channels. To address the ion selectivity of M2, we exploited the coupling of ionic influx and efflux in sealed liposomes. Metal ion fluxes were monitored by proton counterflow, employing a pH probe 1,000 times more sensitive than available Na+ or K+ probes. Even low-pH-activated M2 did not conduct Na+ and K+. The proton selectivity of M2 was estimated to be at least 3 × 106 (over sodium or potassium ions), in agreement with electrophysiological studies. The stringent proton selectivity of M2 suggests that the cytopathology of influenza virus does not involve direct perturbation of cellular sodium or potassium gradients.

scholarly journals Structure and functional characterization of the periplasmic N-terminal polypeptide domain of the sugar-specific ion channel protein (ScrY porin)

2002 ◽  
Vol 11 (6) ◽  
pp. 1565-1574 ◽  
Author(s):  
Jenny Michels ◽  
Armin Geyer ◽  
Viorel Mocanu ◽  
Wolfram Welte ◽  
Alma L. Burlingame ◽  
...  
Keyword(s):  
Ion Channel ◽  
Functional Characterization ◽  
Channel Protein

scholarly journals Biochemical and Functional Characterization of a Novel Prokaryote Ligand-Gated Ion Channel CLIC

2014 ◽  
Vol 106 (2) ◽  
pp. 545a
Author(s):  
Mieke Nys ◽  
Radovan Spurny ◽  
Zander Claes ◽  
Chris Ulens
Keyword(s):  
Ion Channel ◽  
Functional Characterization

scholarly journals TOK Homologue in Neurospora crassa: First Cloning and Functional Characterization of an Ion Channel in a Filamentous Fungus

2003 ◽  
Vol 2 (1) ◽  
pp. 181-190 ◽  
Author(s):  
Stephen K. Roberts
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Neurospora Crassa ◽  
Filamentous Fungus ◽  
Single Channel ◽  
Functional Characterization ◽  
Reversal Potential ◽  
Channel Activity ◽  
Biophysical Properties ◽  
Patch Clamp Technique

ABSTRACT In contrast to animal and plant cells, very little is known of ion channel function in fungal physiology. The life cycle of most fungi depends on the “filamentous” polarized growth of hyphal cells; however, no ion channels have been cloned from filamentous fungi and comparatively few preliminary recordings of ion channel activity have been made. In an attempt to gain an insight into the role of ion channels in fungal hyphal physiology, a homolog of the yeast K+ channel (ScTOK1) was cloned from the filamentous fungus, Neurospora crassa. The patch clamp technique was used to investigate the biophysical properties of the N. crassa K+ channel (NcTOKA) after heterologous expression of NcTOKA in yeast. NcTOKA mediated mainly time-dependent outward whole-cell currents, and the reversal potential of these currents indicated that it conducted K+ efflux. NcTOKA channel gating was sensitive to extracellular K+ such that channel activation was dependent on the reversal potential for K+. However, expression of NcTOKA was able to overcome the K+ auxotrophy of a yeast mutant missing the K+ uptake transporters TRK1 and TRK2, suggesting that NcTOKA also mediated K+ influx. Consistent with this, close inspection of NcTOKA-mediated currents revealed small inward K+ currents at potentials negative of EK. NcTOKA single-channel activity was characterized by rapid flickering between the open and closed states with a unitary conductance of 16 pS. NcTOKA was effectively blocked by extracellular Ca2+, verapamil, quinine, and TEA+ but was insensitive to Cs+, 4-aminopyridine, and glibenclamide. The physiological significance of NcTOKA is discussed in the context of its biophysical properties.

scholarly journals The taste of water

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
W Daniel Tracey
Keyword(s):  
Ion Channel ◽  
Fresh Water ◽  
Channel Protein

Female mosquitos require a specific ion-channel protein to sense the presence of fresh water in which they can lay their eggs.

TGF-β1 enhances Kv2.1 potassium channel protein expression and promotes maturation of cerebellar granule neurons

2011 ◽  
Vol 227 (1) ◽  
pp. 297-307 ◽  
Author(s):  
Jia-Li Zhuang ◽  
Chang-Ying Wang ◽  
Meng-Hua Zhou ◽  
Kai-Zheng Duan ◽  
Yan-Ai Mei
Keyword(s):  
Protein Expression ◽  
Potassium Channel ◽  
Cerebellar Granule Neurons ◽  
Granule Neurons ◽  
Cerebellar Granule ◽  
Channel Protein ◽  
Tgf Β1
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