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Cation selectivity of and cation binding to the cGMP-dependent channel in bovine rod outer segment membranes
The properties of the cGMP-dependent channel present in membrane vesicles prepared from intact isolated bovine rod outer segments (ROS) were investigated with the optical probe neutral red. The binding of neutral red is sensitive to transport of cations across vesicular membranes by the effect of th...
Formato: | Texto |
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Lenguaje: | English |
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The Rockefeller University Press
1990
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2228998/ https://www.ncbi.nlm.nih.gov/pubmed/1700060 |
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collection | PubMed |
description | The properties of the cGMP-dependent channel present in membrane vesicles prepared from intact isolated bovine rod outer segments (ROS) were investigated with the optical probe neutral red. The binding of neutral red is sensitive to transport of cations across vesicular membranes by the effect of the translocated cations on the surface potential at the intravesicular membrane/water interface (Schnetkamp, P. P. M. J. Membr. Biol. 88: 249-262). Only 20-25% of ROS membrane vesicles exhibited cGMP-dependent cation fluxes. The cGMP-dependent channel in bovine ROS carried currents of alkali and earth alkali cations, but not of organic cations such as choline and tetramethylammonium; little discrimination among alkali cations (K greater than Na = Li greater than Cs) or among earth alkali cations (Ca greater than Mn greater than Sr greater than Ba = Mg) was observed. The cation dependence of cGMP-induced cation fluxes could be reasonably well described by a Michaelis-Menten equation with a dissociation constant for alkali cations of about 100 mM, and a dissociation constant for Ca2+ of 2 mM. cGMP-induced Na+ fluxes were blocked by Mg2+, but not by Ca2+, when the cations were applied to the cytoplasmic side of the channel. cGMP-dependent cation fluxes showed a sigmoidal dependence on the cGMP concentration with a Hill coefficient of 2.1 and a dissociation constant for cGMP of 92 microM. cGMP-induced cation fluxes showed two pharmacologically distinct components; one component was blocked by both tetracaine and L-cis diltiazem, whereas the other component was only blocked by tetracaine. |
format | Text |
id | pubmed-2228998 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1990 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-22289982008-04-23 Cation selectivity of and cation binding to the cGMP-dependent channel in bovine rod outer segment membranes J Gen Physiol Articles The properties of the cGMP-dependent channel present in membrane vesicles prepared from intact isolated bovine rod outer segments (ROS) were investigated with the optical probe neutral red. The binding of neutral red is sensitive to transport of cations across vesicular membranes by the effect of the translocated cations on the surface potential at the intravesicular membrane/water interface (Schnetkamp, P. P. M. J. Membr. Biol. 88: 249-262). Only 20-25% of ROS membrane vesicles exhibited cGMP-dependent cation fluxes. The cGMP-dependent channel in bovine ROS carried currents of alkali and earth alkali cations, but not of organic cations such as choline and tetramethylammonium; little discrimination among alkali cations (K greater than Na = Li greater than Cs) or among earth alkali cations (Ca greater than Mn greater than Sr greater than Ba = Mg) was observed. The cation dependence of cGMP-induced cation fluxes could be reasonably well described by a Michaelis-Menten equation with a dissociation constant for alkali cations of about 100 mM, and a dissociation constant for Ca2+ of 2 mM. cGMP-induced Na+ fluxes were blocked by Mg2+, but not by Ca2+, when the cations were applied to the cytoplasmic side of the channel. cGMP-dependent cation fluxes showed a sigmoidal dependence on the cGMP concentration with a Hill coefficient of 2.1 and a dissociation constant for cGMP of 92 microM. cGMP-induced cation fluxes showed two pharmacologically distinct components; one component was blocked by both tetracaine and L-cis diltiazem, whereas the other component was only blocked by tetracaine. The Rockefeller University Press 1990-09-01 /pmc/articles/PMC2228998/ /pubmed/1700060 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/). |
spellingShingle | Articles Cation selectivity of and cation binding to the cGMP-dependent channel in bovine rod outer segment membranes |
title | Cation selectivity of and cation binding to the cGMP-dependent channel in bovine rod outer segment membranes |
title_full | Cation selectivity of and cation binding to the cGMP-dependent channel in bovine rod outer segment membranes |
title_fullStr | Cation selectivity of and cation binding to the cGMP-dependent channel in bovine rod outer segment membranes |
title_full_unstemmed | Cation selectivity of and cation binding to the cGMP-dependent channel in bovine rod outer segment membranes |
title_short | Cation selectivity of and cation binding to the cGMP-dependent channel in bovine rod outer segment membranes |
title_sort | cation selectivity of and cation binding to the cgmp-dependent channel in bovine rod outer segment membranes |
topic | Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2228998/ https://www.ncbi.nlm.nih.gov/pubmed/1700060 |