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

Щелевые соединения представляют собой каналы связи между соседними клетками животных.
Эти каналы состоят из трансмембранных белков, называемых коннексинами. Шесть молекул коннексина образуют гемиканал, называемый коннекзоном.
Гомомерный коннексон содержит шесть копий одного и того же белка коннексина, в то время как гетеромерный коннексон образован различными белками коннексина.
Коннексоны могут динамически диффундировать через мембрану. Когда один коннексон на клеточной мембране сталкивается с другим коннексоном на соседней клетке, они объединяются, образуя полный канал.
Кластеры таких каналов образуют бляшки щелевого соединения, которые позволяют обмениваться ионами, вторичными мессенджерами, сахарами и другими малыми молекулами между клетками.
Разнообразие коннексинов и их комбинаций придает каналу селективность для конкретных молекул.
Транспорт растворенных веществ дополнительно регулируется открытием и закрытием каналов в ответ на различные раздражители, такие как разность напряжений, концентрация ионов кальция и pH.
Например, щелевые соединения в сердечных мышцах реагируют на разницу напряжений и синхронизируют поток ионов между группами мышечных клеток, тем самым вызывая ритмичные сокращения в сердце.

<ol>
	<li>Лэрд, Дейл В. "Жизненный цикл коннексинов в организме здоровья и болезни." Биохимический журнал 394.3 (2006): 527-543.</li>
	<li>Бауэр, Рейнхард и др. "Межклеточная коммуникация: многобелковое семейство белков щелевого соединения иннексина дрозофилы." Химия и биология 12.5 (2005): 515-526.</li>
	<li>Сагер, Росс Э., и Юнг-Юн Ли. «Плазмодесматы с первого взгляда». Журнал клеточной науки 131.11 (2018): jcs209346.</li>
</ol>

Щелевые соединения

Gap Junctions

Цитоплазма соседних клеток животных может обмениваться небольшими молекулами, ионами и вторичными мессенджерами через каналы связи, образующие щелевые контакты. Эти соединения содержат от нескольких сотен до тысяч молекулярных каналов, каждый из которых состоит из двух половин, называемых полуканалами коннексона. Коннексон представляет собой гексамер из шести трансмембранных белков коннексина, которые собираются радиально, образуя пору или канал в центре. Один полуканал коннексона стыкуется с соответствующим коннексоном соседней клетки, образуя канал. Динамика щелевого соединения Коннексины транслируются рибосомой на шероховатой эндоплазматической сети и котрансляционно встраиваются в мембрану ЭР. Затем мономеры транспортируются в сеть Гольджи, где они олигомеризуются. Гексамерные коннексоны транспортируются из сети транс-Гольджи к плазматической мембране через секреторные пузырьки. Коннексоны могут свободно перемещаться по плазматической мембране до тех пор, пока не встретятся с другими коннексонами, образуя кластеры. Таким образом, к периферии растущего кластера постоянно добавляются новые коннексоны, образуя бляшку щелевого соединения. В центре этой бляшки старые коннексоны эндоцитозируются и помечаются для деградации. Таким образом, щелевые соединения представляют собой динамические комплексы с постоянным обменом коннексонов на мембране. Щелевые соединения беспозвоночных Щелевые соединения у беспозвоночных имеют структуру, аналогичную таковой у позвоночных; однако они содержат разные белки, называемые иннексинами (коннексины беспозвоночных). Хотя иннексины имеют сходную трансмембранную структуру, они не имеют гомологичных последовательностей с коннексинами. Они также отличаются от своих собратьев из позвоночных тем, что для формирования полуканала иннексона требуется восемь единиц вместо шести. Двойники в растениях В отличие от тканей животных, где мембраны соседних клеток находятся в непосредственном контакте, клеточные стенки в тканях растений предотвращают прямой контакт соседних плазматических мембран. Таким образом, межклеточная коммуникация и обмен молекул происходят через специализированные соединения, называемые плазмодесмами. Мембрана одной клетки непрерывна с мембраной соседней клетки в этих местах соединения, образуя трубчатый канал диаметром от 20 до 40 нм. Таким образом, цитоплазма соседних клеток смежна, что позволяет регулировать обмен различными небольшими молекулами.

Цитоплазма соседних клеток животных может обмениваться малыми молекулами, ионами и вторичными мессенджерами через каналы связи, которые образуют зазор ...

Education

JoVE Core

Cell Biology

Клеточная биология

Unit 1

Раздел 1

Cell-Cell Interactions

Межклеточные взаимодействия

KEY TERMS AND CONCEPTS

ОСНОВНЫЕ ТЕРМИНЫ И ПОНЯТИЯ

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

cell-adhesion-molecules-types-and-functions

Cell Adhesion Molecules in Tissues

Cell adhesion molecules help cells stick together and work as part of a tissue. They give multicellular organisms physical strength and also help cells send signals across the plasma membrane. These proteins are important for coordinated activity in tissues and organ systems. CAMs are grouped into four main families: integrins, cadherins, selectins, and immunoglobulin-like CAMs, or IgCAMs. Each family supports cell interactions in a different way. Some CAMs help cells attach firmly, while...

structure of cadherins

Cadherins in Cell Junctions and Disease

Cadherins are cell adhesion proteins that help cells stick together and build tissues. Their name comes from their calcium-dependent binding. Early examples were named E-cadherin, P-cadherin, and N-cadherin after the epithelial, placental, and neuronal cells where they were first found. Classical cadherins share similar sequences and structures. Other cadherins, including those involved in cell signaling, are grouped as non-classical cadherins. This diversity comes from multiple cadherin genes...

cadherins in tissue organization

Cadherins Guide Cell Sorting in Tissues

Cadherins help cells sort into the right tissues during development. They are a large superfamily of cell adhesion molecules, with more than 180 variants. Different tissues express specific cadherin combinations, which helps cells recognize and stick to the right neighbors. Cadherins usually bind to the same or a closely related cadherin on another cell. This is called homophilic binding. Because of this matching behavior, cells of the same type tend to group together and form clusters that...

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

Selectins in Immune Cell Capture

Selectins help cells make short, temporary contacts during immune responses. They are cell adhesion molecules that bind carbohydrate ligands on other cells. These rod-like proteins have a long outside region and end in a lectin domain, which binds carbohydrates only when calcium ions are present. Three main selectins are known: L-selectin, P-selectin, and E-selectin. Their names reflect where they are found and how long they are. This tissue specificity helps explain why selectins act in...

immunoglobulin-like cell adhesion molecules

immunoglobulin-like-cell-adhesion-molecules

Ig-CAMs in Neural Growth and Disease

Ig-CAMs, or immunoglobulin-like cell adhesion molecules, are cell surface glycoproteins in the immunoglobulin superfamily. They contain immunoglobulin domains, and some also have fibronectin type III domains. Their Ig domains can be glycosylated to different degrees. These molecules can bind to the same kind of Ig-CAM or to other ligands, such as integrins. Most Ig-CAMs help cells stick together only for a short time. The nectin class is different because it helps form stable junctions,...

overview of cell-cell junctions

Cell Junctions in Tissues

Cell junctions help hold tissues together and let neighboring cells communicate. In multicellular organisms, the three-dimensional shape of tissues depends on interactions between cells and the extracellular matrix. Cell-cell junctions are specialized structures made of multi-protein complexes on one cell that connect with similar complexes on another cell. These junctions are grouped into three main types based on function: occluding, anchoring, and gap junctions. Tight junctions, also called...

adherens junctions

Cell Adhesion in Tissues and Infection

Adherens junctions are strong cell-to-cell anchors that help tissues stay connected. These anchoring junctions work with desmosomes, another type of junction that holds adjacent cells together. In many epithelial and endothelial tissues, adherens junctions form a continuous adhesion belt. In heart muscle, they often appear as clusters that help cells work together for coordinated contraction. Adherens junctions are also dynamic, especially in the cells that line blood vessels. These...

tension response at adherens junctions

How Adherens Junctions Sense Force

Adherens junctions help cells stay attached while they respond to mechanical force. These multi-protein complexes can adapt to tensile force and shear stress. When the force changes, mechanosensory proteins in the junction can change shape. This process is called mechanotransduction. Alpha-catenin is one of the main force-sensing proteins in adherens junctions. It is an allosteric protein, which means its shape affects how it works. Alpha-catenin has three VH, or vinculin homology, domains...

desmosomes

Desmosomes and Cell Anchoring

Desmosomes are cell junctions that anchor cells together. They are button-like structures that create an interlinked network of intermediate filaments across cells. This strong link helps tissues resist mechanical stress and maintain tissue integrity. Desmosomes are built from multiple proteins. Their core includes desmosomal cadherins, which are adhesion proteins that bind to cadherins on neighboring cells. The two desmosomal cadherins are desmogleins and desmocollins. These transmembrane...

tight junctions

Tight Junction Proteins and Cell Barriers

Tight junction proteins form seals between neighboring cells. These molecular barriers help stop fluids, ions, and other small solutes from leaking across body cavities and tissue compartments in multicellular organisms. They are an important part of cell barriers in places where controlled movement matters. The main tight junction proteins are claudin and occludin. Other proteins include tricellulin and JAM, which stands for junctional adhesion molecule. Most of these proteins are 4-pass...

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 Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

Cell Communication Through Gap Junctions

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