Name: cell communication through gap junctions
Uploaded: 2023-04-30T11:55:54.000Z
Duration: 1 min 27 s
Channel: JoVE

Las uniones gap son canales de comunicación entre células animales adyacentes.
Estos canales están compuestos por proteínas transmembrana llamadas conexinas. Seis moléculas de conexina forman un hemicanal llamado conexión .
Una conexión homomérica comprende seis copias de la misma proteína de conexina, mientras que una conexión heteromérica está formada por diferentes proteínas de conexina.
Las conexiones pueden difundirse dinámicamente a través de la membrana. Cuando una conexión en una membrana celular se encuentra con otra conexión en la célula adyacente, se emparejan para formar un canal completo.
Los grupos de dichos canales forman las placas de unión de brecha que permiten el intercambio de iones, mensajeros secundarios, azúcares y otras moléculas pequeñas entre las células.
La diversidad de conexinas y sus combinaciones confiere selectividad de canal para moléculas específicas.
El transporte de solutos se regula aún más mediante la apertura y el cierre de canales en respuesta a diversos estímulos, como la diferencia de voltaje, la concentración de iones de calcio y el pH.
Por ejemplo, las uniones gap en los músculos del corazón responden a las diferencias de voltaje y sincronizan el flujo de iones entre grupos de células musculares, generando así contracciones rítmicas en el corazón.

<ol>
	<li>Laird, Dale W. "Ciclo de vida de las conexinas en la salud y la enfermedad". Revista Bioquímica 394.3 (2006): 527-543.</li>
	<li>Bauer, Reinhard, et al. "Comunicación intercelular: la familia multiproteica de Drosophila innexin de proteínas de unión gap". Química y biología 12.5 (2005): 515-526.</li>
	<li>Sager, Ross E. y Jung-Youn Lee. "Plasmodesmos de un vistazo". Revista de ciencia celular 131.11 (2018): jcs209346.</li>
</ol>

uniones gap

Gap Junctions

El citoplasma de las células animales adyacentes puede intercambiar pequeñas moléculas, iones y mensajeros secundarios a través de los canales de comunicación que forman las uniones comunicantes. Estas uniones comprenden entre unos cientos y miles de canales moleculares, cada uno de los cuales está formado por dos mitades, denominadas hemicanal de conexión. Una conexón es un hexámero de seis proteínas conexinas transmembrana, que se ensamblan radialmente, formando así un poro o canal en el centro. Un hemicanal de conexión se acopla con una conexión correspondiente en la celda adyacente, completando el canal.

Dinámica de la unión de brechas

Las conexinas son traducidas por el ribosoma en el retículo endoplásmico rugoso y se insertan cotraduccionalmente en la membrana del RE. entonces, los monómeros se transportan a la red de Golgi, donde se oligomerizan. Las conexiones hexaméricas se transportan desde la red trans-Golgi a la membrana plasmática a través de vesículas secretoras. Las conexiones pueden moverse libremente a lo largo de la membrana plasmática hasta que se encuentran con otras conexiones, formando grupos. Por lo tanto, a un grupo en crecimiento se le agregan continuamente nuevas conexiones a su periferia, formando una placa de uniones comunicantes. En el centro de esta placa, las conexiones antiguas están endocitadas y marcadas para su degradación. Las uniones en hendidura son, por tanto, conjuntos dinámicos con un recambio constante de conexiones en la membrana.

Uniones de espacios de invertebrados

Las uniones comunicantes en los invertebrados tienen una estructura similar a la de los vertebrados; sin embargo, comprenden diferentes proteínas llamadas innexinas (conexinas de invertebrados). Aunque las innexinas tienen una estructura transmembrana similar, no comparten homología de secuencia con las conexinas. También se diferencian de sus homólogos vertebrados en que requieren ocho unidades para formar un hemicanal innexon en lugar de seis.

Contrapartes en plantas

A diferencia de los tejidos animales, donde las membranas de las células adyacentes están en contacto directo, las paredes celulares de los tejidos vegetales impiden el contacto directo de las membranas plasmáticas adyacentes. La comunicación intercelular y el intercambio de moléculas se producen así a través de uniones especializadas llamadas plasmodesmos. La membrana de una célula es continua con la de la célula adyacente en estas uniones, formando un canal tubular de aproximadamente 20 a 40 nm de diámetro. Por tanto, el citoplasma de las células adyacentes es contiguo, lo que permite el intercambio regulado de varias moléculas pequeñas.

Uniones gap

El citoplasma de las células animales adyacentes puede intercambiar pequeñas moléculas, iones y mensajeros secundarios a través de los canales de comunicación que forman la brecha ...

Education

Educación

JoVE Core

Cell Biology

Biología Celular

Unit 1

Unidad 1

Cell-Cell Interactions

Interacciones célula-célula

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

cell communication through gap junctions

Gap junctions let adjacent animal cells share small molecules, ions, and secondary messengers. These communication channels connect the cytoplasm of neighboring cells. They are built from many molecular channels, often from a few hundred to thousands in one junction.

Each channel is made of two halves called connexon hemichannels. A connexon is a hexamer, meaning it is formed by six transmembrane connexin proteins. The six proteins arrange in a ring and create a pore in the center. One connexon from one cell docks with a matching connexon from the neighboring cell to complete the channel.

Connexins are made on ribosomes attached to the rough endoplasmic reticulum. They are inserted into the ER membrane as they are made. The monomers then move to the Golgi network, where they oligomerize, or assemble into larger units. The hexameric connexons travel from the trans-Golgi network to the plasma membrane in secretory vesicles.

Once at the membrane, connexons can move freely until they meet other connexons. They cluster together and form a gap junction plaque. New connexons keep joining at the outer edge of the plaque. At the center, older connexons are endocytosed and marked for degradation, so gap junctions keep turning over over time.

Invertebrate gap junctions are similar in shape to vertebrate ones, but they use different proteins called innexins. Innexins are not sequence homologs of connexins, even though they have a similar transmembrane structure. They also form hemichannels with eight units instead of six.

Plants use plasmodesmata instead of gap junctions because their cell walls keep adjacent plasma membranes from touching directly. These junctions allow intercellular communication and the exchange of molecules between plant cells. The membrane of one cell continues into the next, forming a tubular channel about 20 to 40 nm wide. This makes the cytoplasm of neighboring cells continuous and allows the regulated movement of small molecules.

Cell Communication Through Gap Junctions

cell adhesion molecules - types and functions

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catenins

Catenins in Cell Junctions and Signaling

Catenins help cells stay connected and also support signaling inside the body. These proteins act as linker proteins in cell junction complexes because they have multiple binding domains and flexible structures. Most catenins contain a protein sequence called the armadillo repeat, so they are also known as armadillo proteins. Alpha-catenin is the main exception. Catenins bind to cell adhesion molecules such as cadherins. They then connect cadherins to cytoskeletal proteins, and the exact link...

selectins

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Ig-CAMs in Neural Growth and Disease

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overview of cell-cell junctions

Cell Junctions in Tissues

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adherens junctions

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How Adherens Junctions Sense Force

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gap junctions

Gap junctions let adjacent animal cells share small molecules, ions, and secondary messengers. These communication channels connect the cytoplasm of neighboring cells. They are built from many molecular channels, often from a few hundred to thousands in one junction. Each channel is made of two halves called connexon hemichannels. A connexon is a hexamer, meaning it is formed by six transmembrane connexin proteins. The six proteins arrange in a ring and create a pore in the center. One...

key terms and concepts

Learn how gap junctions connect animal cells, how connexins build connexon channels, and how innexins and plasmodesmata support cell communication.

Cell Communication Through Gap Junctions | JoVE K12

cell biology

JoVE Core Biología Celular ilustra procesos celulares complejos mediante completos vídeos animados fáciles de entender. Esta colección se centra en los componentes esenciales de las células y su funcionamiento, incluyendo los orgánulos y las membranas, el transporte celular y el metabolismo energético celular. Todo este material se complementa con los vídeos de científicos en acción, que muestran la aplicación de la biología celular en experimentos reales de investigación.

Cell Communication Through Gap Junctions

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