Ionic Channels
Mostrando 25-36 de 315 artigos, teses e dissertações.
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25. Channel protein engineering: synthetic 22-mer peptide from the primary structure of the voltage-sensitive sodium channel forms ionic channels in lipid bilayers.
A synthetic 22-mer peptide that mimics the sequence of a putative pore segment of the voltage-dependent sodium channel forms transmembrane ionic channels in lipid bilayers. Several features of the authentic sodium channel are exhibited by the synthetic peptide: (i) The single channel conductance of the most frequent event is 20 pS in 0.5 M NaCl. (ii) The sin
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26. Flux, coupling, and selectivity in ionic channels of one conformation.
Ions crossing biological membranes are described as a concentration of charge flowing through a selective open channel of one conformation and analyzed by a combination of Poisson and Nernst-Planck equations and boundary conditions, called the PNP theory for short. The ion fluxes in this theory interact much as ion fluxes interact in biological channels and
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27. Faster voltage-dependent activation of Na+ channels in growth cones versus somata of neuroblastoma N1E-115 cells.
Kinetics of voltage-gated ionic channels fundamentally reflect the response of the channels to local electric fields. In this report cell-attached patch-clamp studies reveal that the voltage-dependent activation rate of sodium channels residing in the growth cone membrane differs from that of soma sodium channels in differentiating N1E-115 neuroblastoma cell
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28. Barium modulates the gating of batrachotoxin-treated Na+ channels in high ionic strength solutions.
Batrachotoxin-activated rat brain Na+ channels were reconstituted in neutral planar phospholipid bilayers in high ionic strength solutions (3 M NaCl). Under these conditions, diffuse surface charges present on the channel protein are screened. Nevertheless, the addition of extracellular and/or intracellular Ba2+ caused the following alterations in the gating
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29. Synporins--synthetic proteins that emulate the pore structure of biological ionic channels.
A class of proteins that mimic the fundamental pore structure of authentic ionic channels has been designed, synthesized, and characterized. The design is based on our earlier result that a 23-mer peptide with the sequence of the M2 segment of the Torpedo californica acetylcholine receptor delta subunit--Glu-Lys-Met-Ser-Thr-Ala-Ile-Ser-Val-Leu-Leu-Ala-Gln-Al
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30. Channel protein engineering: Synthetic 22-mer peptide from the primary structure of the voltage-sensitive sodium channel forms ionic channels in lipid bilayers
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31. Functional role of L-type Cav1.3 Ca2+ channels in cardiac pacemaker activity
The spontaneous activity of pacemaker cells in the sino-atrial node (SAN) controls the heart rhythm and rate under physiological conditions. Pacemaker activity in SAN cells is due to the presence of the diastolic depolarization, a slow depolarization phase that drives the membrane voltage from the end of an action potential to the threshold of a new action p
The National Academy of Sciences.
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32. On the structural basis for ionic selectivity among Na+, K+, and Ca2+ in the voltage-gated sodium channel.
Voltage-sensitive sodium channels and calcium channels are homologous proteins with distinctly different selectivity for permeation of inorganic cations. This difference in function is specified by amino acid residues located within P-region segments that link presumed transmembrane elements S5 and S6 in each of four repetitive Domains I, II, III, and IV. By
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33. Effect of changing temperature on the ionic permeation through the cyclic GMP-gated channel from vertebrate photoreceptors.
Native cGMP-gated channels were studied in rod outer segments of the larval tiger salamander Ambystoma tigrinum. The alpha subunit of the cGMP-gated channel from bovine rods, here referred to as the wild type (w.t.), and mutant channels were heterologously expressed in Xenopus laevis oocytes. These channels were studied in excised membrane patches in the ins
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34. Permeation in ionic channels: a statistical rate theory approach.
A novel way to model permeation through ionic channels is formulated. Our method does not require that equilibrium exists in the channel or at the channel interfaces. In addition, the potential profile does not need to be specified and the assumption of constant field across the membrane does not need to be made. Our formulation relies on statistical rate th
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35. Matrix protein from Escherichia coli outer membranes forms voltage-controlled channels in lipid bilayers.
Matrix protein from Escherichia coli was integrated into planar lipid bilayers. The incorporated protein generates aqueous channels across these membranes. Channels are induced irreversibly by voltage, and their number is proportional to the protein content of the membrane and stays constant over hours. They are uniform in size, with a diameter of about 1 nm
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36. Effects of drugs on acetylcholine-activated ionic channels of internally perfused chick myoballs.
The effects of intracellular application of three compounds - QX314, N-ethylguanidine and N-octylguanidine - on the acetylcholine-activated ionic channels in chick myoballs were examined. Voltage-clamped myoballs were internally perfused using the suction-pipette technique. Changes in the internal ionic environment of myoballs were demonstrated by: (1) alter