Name: integrins in cell adhesion
Uploaded: 2023-04-30T11:54:12.000Z
Duration: 1 min 10 s
Channel: JoVE

Integrins are a family of cell-adhesion receptors that bind ligands in the extracellular matrix or ECM to mediate cell-matrix adhesions.
They transition between an active and an inactive state. In the active form, they serve as mechanical linkers connecting the cytoskeleton to the extracellular matrix.
Integrin comprises noncovalently associated alpha and beta glycoprotein subunits, forming a transmembrane heterodimer.
The intracellular C-terminal tail of the beta subunit interacts with actin filaments in the cytosol through adaptor proteins such as talin and paxillin. Integrin&#8217;s large N-terminal extracellular domains bind to specific amino acid sequence motifs in ECM proteins, such as the RGD sequence in fibronectin.
The adhesion complex formed transmits signals bidirectionally across the plasma membrane with the help of effector proteins, thus facilitating cell motility, growth, and survival.

integrinen

Integrins

Dierlijke en protozoaire cellen hebben geen celwanden die helpen hun vorm te behouden en structurele stabiliteit te bieden. In plaats daarvan scheiden deze eukaryotische cellen een kleverige massa koolhydraten en eiwitten af in de ruimtes tussen aangrenzende cellen. Dit netwerk van eiwitten en moleculen wordt een extracellulaire matrix of ECM genoemd.

Sommige ECM-eiwitten verzamelen zich in een basaalmembraan waaraan de overige componenten hechten. Proteoglycanen vormen doorgaans het grootste deel van de ECM, terwijl vezelachtige eiwitten, zoals collageen, voor kracht zorgen. Zowel proteoglycanen als collageen zijn gehecht aan fibronectine-eiwitten, die op hun beurt zijn gehecht aan integrale membraaneiwitten die integrinen worden genoemd.

Zoogdierintegrines zijn heterodimere transmembraanadhesiereceptoren die α- en β-glycoproteïnesubeenheden omvatten. Achttien verschillende α-ketengenen en acht verschillende β-ketengenen dimeriseren in verschillende combinaties, wat resulteert in 24 soorten integrinen die specifiek zijn voor gewervelde dieren. Ze omspannen het membraan en interageren met eiwitten in het cytosol en de ECM. De α-subeenheid bevat een zevenbladig β-propellerkopdomein, terwijl de β-subeenheid een I-achtig hoofddomein heeft; samen binden ze ligand. De ligandbindende kop is verbonden met twee pootachtige structuren, één uit elke subeenheid. De β-subeenheid interageert met het cytoskeleteiwit en helpt signalen in en uit de cel over te brengen.

Integrinen

Animal and protozoan cells do not have cell walls to help maintain shape and provide structural stability. Instead, these eukaryotic cells secrete a ...

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Cell Biology

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Cell-Matrix Interactions

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integrins in cell adhesion

Integrins help animal and protozoan cells attach to the extracellular matrix, or ECM. These cells do not have cell walls, so the ECM helps maintain shape and provide structural stability. The ECM is a sticky network of carbohydrates and proteins found between adjacent cells.

Some ECM proteins form a basement membrane, and other ECM parts adhere to it. Proteoglycans make up much of the ECM, while fibrous proteins such as collagen give it strength. Fibronectin connects proteoglycans and collagen to integral membrane proteins called integrins.

Integrins are heterodimeric transmembrane adhesion receptors in mammals. That means each receptor has two different glycoprotein subunits, an alpha subunit and a beta subunit. Eighteen alpha-chain genes and eight beta-chain genes can pair in different ways to make 24 vertebrate integrins.

These receptors span the cell membrane and link the ECM to the cytosol. The alpha subunit has a seven-bladed beta-propeller head domain, and the beta subunit has an I-like head domain. Together, these head domains bind ligand, and the two leg-like parts connect the head to the membrane.

The beta subunit also interacts with a cytoskeletal protein. This helps integrins transmit signals into and out of the cell. Their structure and connections make them important for adhesion and communication in cells that rely on the ECM.

Integrins in Cell Adhesion

overview of cell-matrix interactions

ECM Proteins and Cell Signaling

The extracellular matrix, or ECM, is the material that helps hold cells together in a tissue. It also lets cells in that tissue communicate with one another. The ECM contains proteins such as fibronectin, collagen, and laminin. Collagen is the most abundant protein in this space. Collagen fibers are woven together with proteoglycans, which are protein molecules with carbohydrates attached. This mix gives the ECM its structure. It also supports cell migration and provides a scaffold for cell...

integrins

Integrins help animal and protozoan cells attach to the extracellular matrix, or ECM. These cells do not have cell walls, so the ECM helps maintain shape and provide structural stability. The ECM is a sticky network of carbohydrates and proteins found between adjacent cells. Some ECM proteins form a basement membrane, and other ECM parts adhere to it. Proteoglycans make up much of the ECM, while fibrous proteins such as collagen give it strength. Fibronectin connects proteoglycans and collagen...

activation of integrins

How Integrins Link Cells to Their Environment

Integrins help cells connect with their environment and send signals across the cell membrane. They can carry information from outside the cell to the inside, or from inside the cell to the outside. These two paths are called outside-in signaling and inside-out signaling. In outside-in signaling, molecules in the extracellular space bind to exposed ligand-binding sites on integrins. A ligand is a molecule that binds to a protein. This binding makes the inactive integrin change shape and become...

intracellular signaling affects focal adhesions

intracellular-signaling-affects-focal-adhesions

Integrins Trigger Focal Adhesion Signaling

Integrins trigger focal adhesion signaling at the cell membrane. These membrane receptors sit in the phospholipid bilayer with hydrophobic regions that match the membrane interior. They provide attachment sites for outside signals such as hormones and growth factors. When these effectors bind and become active, integrins can start response pathways inside the cell. Some integrin-driven pathways support cell growth and help cells survive. The signal begins at the membrane, but G-proteins and...

anchoring junctions

Cell Adhesion in Anchoring Junctions

Anchoring junctions are multiprotein complexes that help cells connect to other cells and to the extracellular matrix. They sit on the lateral and basal surfaces of cells. These junctions create strong, flexible links that help maintain tissue stability and integrity. Focal adhesions often form when cells interact with the extracellular matrix, or ECM, substrata. These contacts can start signal transduction through kinase cascades and other pathways. Together, these junctions help cells stay...

cell-matrix's response to mechanical forces

cell-matrix-s-response-to-mechanical-forces

Focal Adhesions and Cell Mechanics

Focal adhesions help animal cells connect to the extracellular matrix and sense mechanical forces. The extracellular matrix, or ECM, sits outside cells and helps tissues withstand stress. It also sends signals from outside the cell to the inside. The ECM is large and its makeup changes from one tissue to another. In loose connective tissue, reticular fibers and ground substance form the ECM. In bone tissue, collagen and bone minerals make up the ECM. Anchoring junctions hold a cell to the...

key terms and concepts

Learn how integrins connect the extracellular matrix to the cell membrane, support cell shape, and help transmit signals in animal and protozoan cells.

Integrins in Cell Adhesion | 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.

Integrins in Cell Adhesion

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