{"id":38487,"date":"2018-03-09T09:38:04","date_gmt":"2018-03-09T09:38:04","guid":{"rendered":"https:\/\/www.deberes.net\/tesis\/sin-categoria\/determinantes-moleculares-de-la-interaccion-de-los-canales-de-k-con-los-cationes-extracelulares\/"},"modified":"2018-03-09T09:38:04","modified_gmt":"2018-03-09T09:38:04","slug":"determinantes-moleculares-de-la-interaccion-de-los-canales-de-k-con-los-cationes-extracelulares","status":"publish","type":"post","link":"https:\/\/www.deberes.net\/tesis\/ciencias-de-la-vida\/determinantes-moleculares-de-la-interaccion-de-los-canales-de-k-con-los-cationes-extracelulares\/","title":{"rendered":"Determinantes moleculares de la interaccion de los canales de k+ con los cationes extracelulares."},"content":{"rendered":"<h2>Tesis doctoral de <strong> Gracia Patricia Ortega Saenz <\/strong><\/h2>\n<p>Los canales de potasio dependientes de voltage son proteinas tetram\u00e9ricas que poseen amino\u00e1cidos cargados negativamente (e y d) al ph fisiol\u00f3gico.En el trabajo de esta tesis hemos estudiado el papel funcional de algunos de estos res\u00edduos aminoac\u00eddicos localizados en la superficie externa de estas proteinas, realizando mutaciones del canal shaker y expresandolas de forma transitoria en c\u00e9lulas cho. La neutralizaci\u00f3n de la mayor\u00eda de las cargas negativas externas no afectaron ni a los mecanismos de compuesta ni la conducci\u00f3n atrav\u00e9s del poro del canal. Sin embargo la neutralizaci\u00f3n del glut\u00e1mico en posici\u00f3n 418 (mutante e418q) produjo un canal con una cin\u00e9tica de anactivaci\u00f3n \u00abtipo c\u00bb100 veces m\u00e1s r\u00e1pida que la del canal nativo. Igualmente la constante de cierre del canal se redujo unas cinco veces, no afectandose para nada la cin\u00e9tica de activaci\u00f3n del canal. El potasio extracelular produjo un incremento del n\u00famero de canales abiertos as\u00ed como un en lentecimiento de las cineticas de inactivaci\u00f3n y cierre. por el contrario la mutaci\u00f3n e418d que modifica el res\u00edduo en esta posici\u00f3n sin modificar la carga, dio lugar a un canal sin diferencias cin\u00e9ticas apreciables respecto al canal silvestre. Estos datos indican que elglutamato en posici\u00f3n 418, altamente conservado en los canales de potasio dependientes delpotencial de membrana, determina el flujo de iones atrav\u00e9s del canal, el numero de canales que abre en respuesta a una determianda despolarizaci\u00f3n y las cin\u00e9ticas de cierre e inactivaci\u00f3n. El mecanismo que postulamos para explicar estos efectos se basa en el hecho de que la carga negativa localizada en la zona externa del canal pr\u00f3xima al poro de conducci\u00f3no incluso en la boca de este, actua colectando cationes (fundamentamente monovalentes) en la boca del canal, aumentando con ello la probabilidad de ocupaci\u00f3n del poro por potasio. La eliminaci\u00f3n de esta carga negativa disminuye por tanto la probabilidad de<\/p>\n<p>&nbsp;<\/p>\n<h3>Datos acad\u00e9micos de la tesis doctoral \u00ab<strong>Determinantes moleculares de la interaccion de los canales de k+ con los cationes extracelulares.<\/strong>\u00ab<\/h3>\n<ul>\n<li><strong>T\u00edtulo de la tesis:<\/strong>\u00a0 Determinantes moleculares de la interaccion de los canales de k+ con los cationes extracelulares. <\/li>\n<li><strong>Autor:<\/strong>\u00a0 Gracia Patricia Ortega Saenz <\/li>\n<li><strong>Universidad:<\/strong>\u00a0 Sevilla<\/li>\n<li><strong>Fecha de lectura de la tesis:<\/strong>\u00a0 20\/07\/1998<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<h3>Direcci\u00f3n y tribunal<\/h3>\n<ul>\n<li><strong>Director de la tesis<\/strong>\n<ul>\n<li>Antonio  Gonzalo Castellano Orozco<\/li>\n<\/ul>\n<\/li>\n<li><strong>Tribunal<\/strong>\n<ul>\n<li>Presidente del tribunal: ana Ilunda\u00edn larra\u00f1eta <\/li>\n<li>Emilio Fernandez reyes (vocal)<\/li>\n<li>josefina Cano Garc\u00eda (vocal)<\/li>\n<li>mar\u00ed\u00a7al Pastor anglada (vocal)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Tesis doctoral de Gracia Patricia Ortega Saenz Los canales de potasio dependientes de voltage son proteinas tetram\u00e9ricas que poseen amino\u00e1cidos [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center 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