Ion Selective Membranes
Mostrando 13-24 de 64 artigos, teses e dissertações.
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13. A TRP homolog in Saccharomyces cerevisiae forms an intracellular Ca2+-permeable channel in the yeast vacuolar membrane
The molecular identification of ion channels in internal membranes has made scant progress compared with the study of plasma membrane ion channels. We investigated a prominent voltage-dependent, cation-selective, and calcium-activated vacuolar ion conductance of 320 pS (yeast vacuolar conductance, YVC1) in Saccharomyces cerevisiae. Here we report on a gene,
The National Academy of Sciences.
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14. Ion channels from synaptic vesicle membrane fragments reconstituted into lipid bilayers.
Cholinergic synaptic vesicles were isolated from the electric organ of Torpedo californica. Vesicle membrane proteins were reconstituted into planar lipid bilayers by the nystatin/ergosterol fusion technique. After fusion, a variety of ion channels were observed. Here we identify four channels and describe two of them in detail. The two channels share a cond
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15. Distribution of chloride and potassium in cellular and luminal compartments of control and drug-treated turtle thyroid.
Chloride and potassium activities inside the lumen and the transepithelial potentials of control and drug-treated turtle thyroid follicles were determined simultaneously by ion-selective and conventional 3 M-KCl micro-electrodes, respectively. Water and electrolyte contents of these thyroid tissues were determined chemically after each experiment. Cellular a
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16. Gated, ion-selective channels observed with patch pipettes in the absence of membranes: novel properties of a gigaseal.
Gigaohm seals made between patch pipettes and hydrophobic substrates have a finite conductance which are cation-selective and capable of producing quantized gating indistinguishable from the gating of biological ion channels. The selectivity sequence and streaming potentials of these seals suggests the existence of a pore of similar dimensions to the nicotin
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17. Ion selectivity of gram-negative bacterial porins.
Twelve different porins from the gram-negative bacteria Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, and Yersinia pestis were reconstituted into lipid bilayer membranes. Most of the porins, except outer membrane protein P, formed large, water-filled, ion-permeable channels with a single-channel conductance between 1.5 and 6 nS in 1 M KCl
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18. Antimicrobial defensin peptides form voltage-dependent ion-permeable channels in planar lipid bilayer membranes.
Defensins are cationic, cysteine-rich peptides (Mr = 3500-4000) found in the cytoplasmic granules of neutrophils and macrophages. These peptides possess broad antimicrobial activity in vitro against bacteria, fungi, tumor cells, and enveloped viruses, and they are believed to contribute to the "oxygen-independent" antimicrobial defenses of neutrophils and ma
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19. H+/solute-induced intracellular acidification leads to selective activation of apical Na+/H+ exchange in human intestinal epithelial cells
The intestinal absorption of many nutrients and drug molecules is mediated by ion-driven transport mechanisms in the intestinal enterocyte plasma membrane. Clearly, the establishment and maintenance of the driving forces — transepithelial ion gradients — are vital for maximum nutrient absorption. The purpose of this study was to determine the nature of i
American Society for Clinical Investigation.
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20. Comparison of the ion channel characteristics of proapoptotic BAX and antiapoptotic BCL-2
The BCL-2 family of proteins is composed of both pro- and antiapoptotic regulators, although its most critical biochemical functions remain uncertain. The structural similarity between the BCL-XL monomer and several ion-pore-forming bacterial toxins has prompted electrophysiologic studies. Both BAX and BCL-2 insert into KCl-loaded vesicles in a pH-dependent
The National Academy of Sciences of the USA.
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21. Equilibrium Potentials of Membrane Electrodes
A simple thermodynamic theory of the equilibrium potentials of membrane electrodes is formulated and applied to the glass electrode for measurement of pH. The new formulation assumes the selective adsorption or binding of specific ions on the surface of the membrane which may or may not be permeable to the ion, and includes the conventional derivation based
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22. Electrophysiological Analysis of Cloned Cyclic Nucleotide-Gated Ion Channels1
Electrophysiological studies were conducted on the cloned plant cyclic nucleotide-gated ion channels AtCNGC2 and AtCNGC1 from Arabidopsis, and NtCBP4 from tobacco (Nicotiana tobacum). The nucleotide coding sequences for these proteins were expressed in Xenopus laevis oocytes or HEK 293 cells. Channel characteristics were evaluated using voltage clamp analysi
American Society of Plant Physiologists.
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23. An ion-channel forming protein produced by Entamoeba histolytica.
We have identified a remarkable ion-channel forming material in virulent strains of Entamoeba histolytica that may be responsible for many of the symptoms associated with amoebic dysentery. A polypeptide that we refer to as amoebapore is shed into the growth media and is also found within the amoeba in a high speed sedimentable fraction. Amoebapore has the d
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24. Aerolysin of Aeromonas sobria: evidence for formation of ion-permeable channels and comparison with alpha-toxin of Staphylococcus aureus.
Aerolysin from Aeromonas sobria AB3 was isolated and purified. The pure toxin formed sodium dodecyl sulfate-insoluble oligomers in a lipidic environment. The addition of aerolysin to the aqueous phase bathing lipid bilayer membranes resulted in the formation of ion-permeable channels which had a single-channel conductance of about 70 pS in 0.1 M KCl. This de