Video Experimental Relacionado
Updated: Jul 5, 2026
11:17
Fundamental Technical Elements of Freeze-fracture/Freeze-etch in Biological Electron Microscopy
Published on: September 11, 2014
Localización molecular de un sitio de unión iónica dentro del poro de los canales de sodio de los mamíferos
P H Backx1, D T Yue, J H Lawrence
1Department of Medicine, Johns Hopkins University, Baltimore, MD 21205.
Science (New York, N.Y.)
|July 10, 1992
Resumen
Los iones de cadmio bloquean los canales de sodio, con mayor afinidad por los canales cardíacos que por los canales del músculo esquelético. Una mutación específica alteró esta susceptibilidad, revelando un residuo crítico en el poro del canal.
Área de la Ciencia:
- La biofísica es la biofísica.
- Biología Molecular Biología Molecular
- Farmacología Farmacología.
Sus antecedentes:
- Los canales de sodio son cruciales para la excitabilidad celular en varios tejidos.
- Se sabe que los iones de cadmio interactúan y bloquean los canales de sodio.
- La tetrodotoxina (TTX) es un bloqueador específico utilizado para diferenciar los subtipos de canales de sodio.
Objetivo del estudio:
- Para investigar el bloqueo diferencial de las isoformas de los canales de sodio por los iones de cadmio.
- Para determinar el papel de los residuos específicos en la unión del cadmio y la función del canal.
- Para localizar el sitio de unión del cadmio dentro del poro del canal de sodio.
Principales métodos:
- Utilizó la teoría de la velocidad de reacción química para analizar el bloqueo de iones de cadmio.
- Se examinaron canales de sodio de tipo silvestre y mutantes, incluidas las isoformas del músculo cardíaco y esquelético.
- Investigó los efectos del cadmio y la tetrodotoxina (TTX) en la actividad del canal.
Principales resultados:
- El cadmio exhibió una afinidad significativamente mayor para el canal de sodio cardíaco resistente al TTX en comparación con la isoforma del músculo esquelético sensible al TTX.
- Una mutación (de Tyr401 a Cys) en el canal del músculo esquelético imitaba la susceptibilidad del canal cardíaco al cadmio, pero confería resistencia al TTX.
- El sitio de unión del cadmio se localizó a aproximadamente el 20% de la profundidad del campo eléctrico del poro.
Conclusiones:
- Residuos específicos de aminoácidos dictan la sensibilidad diferencial de los canales de sodio al cadmio.
- El residuo crítico identificado juega un papel clave en la estructura de los poros del canal de sodio y la permeación iónica.
- Esta investigación proporciona información sobre los mecanismos moleculares de la modulación del canal de sodio por los metales pesados.
Más Videos Relacionados
Videos de Conceptos Relacionados
01:19Contact-dependent Signaling
Contact-dependent signaling, as the name suggests, requires that communicating cells be in direct contact with each other. This is achieved either through receptor-ligand interactions or by specialized cytoplasmic channels that allow the flow of small molecules between cells. In animal cells, channels called gap junctions facilitate contact-dependent signaling in certain tissues, whereas, plasmodesmata perform a similar function in plants.
Gap Junctions
In animal cells, gap junctions are formed...
Gap Junctions
In animal cells, gap junctions are formed...
01:37Gap Junctions
Multicellular organisms employ a variety of ways for cells to communicate with each other. Gap junctions are specialized proteins that form pores between neighboring cells in animals, connecting the cytoplasm between the two, and allowing for the exchange of molecules and ions. They are found in a wide range of invertebrate and vertebrate species, mediate numerous functions including cell differentiation and development, and are associated with numerous human diseases, including cardiac and...
00:59Mechanisms of Membrane Domain Formation
Different physical properties of lipids and proteins allow them to localize and form distinct islands or domains in the membrane. Some membrane domains are formed due to protein-protein interactions, whereas others are formed due to the presence of specific lipids such as sphingolipids and sterols—for example, large proteins, such as bacteriorhodopsin, aggregate and create distinct domains.
Another mechanism for membrane domain formation involves membrane proteins interacting with cytoskeletal...
Another mechanism for membrane domain formation involves membrane proteins interacting with cytoskeletal...
01:28Protein Translocation Machinery on the ER Membrane
The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into the ER membrane.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
01:29Tight Junctions
Tight junctions are molecular seals between cells that prevent the leaking of fluids, ions, and other small solutes across cavities and compartments in multicellular organisms. They are mainly composed of claudin and occludin transmembrane proteins, and other proteins such as tricellulin and JAM (junctional adhesion molecule). All these proteins are 4-pass transmembrane proteins, except JAM, which is a single-pass transmembrane protein belonging to the immunoglobulin superfamily. The...
01:27Gap Junctions
The cytoplasm of adjacent animal cells can exchange small molecules, ions, and secondary messengers via the communication channels which form the gap junctions. These junctions comprise a few hundred to thousands of molecular channels, each made of two halves, called the connexon hemichannel. A connexon is a hexamer of six transmembrane connexin proteins, which assemble radially, thus forming a pore or channel in the center. One connexon hemichannel docks with a corresponding connexon on the...