Name: ligand binding in endocytosis
Uploaded: 2023-06-23T15:38:45.000Z
Duration: 1 min 20 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Biology

BIO.5

BIO.5.C

Receptor-Mediated Endocytosis

Receptor-mediated endocytosis is a form of endocytosis where molecules, including metabolites, hormones, and nutrients, are internalized through their specific cell-surface receptors.
Once a molecule binds to its specific receptor on the cell membrane, the membrane bends inwards. Then, clathrin triskelions, structural proteins, bind to adaptor proteins&#160; and polymerize to form a clathrin-coated pit.
Other membrane-bending and fusion proteins are recruited to the neck of the clathrin-coated pit and pinch it off. The coating is rapidly released and the naked vesicle fuses with an early endosome.&#160;
The early endosome has two domains&#8212;tubular and vacuolar, with different internal pHs. The low pH of the vacuolar domain causes the endocytosed ligand to be released from its receptor.
While the ligand is retained in the vacuolar domain and is later processed, the associated receptor remains in the tubular domain due to the large surface area to volume ratio of the tubules. &#160;The receptor is then transported back to the cell membrane.

receptor-mediated endocytosis

Receptor-mediated endocytosis is when bulk amounts of specific molecules are imported into a cell after binding to cell surface receptors. The molecules bound to these receptors are taken into the cell through inward folding of the cell surface membrane, which is eventually pinched off into a vesicle within the cell. Structural proteins, such as clathrin, coat the budding vesicle.
Clathrin-Mediated Endocytosis of LDL
One well-characterized example of receptor-mediated endocytosis is the transport of low-density lipoproteins (LDL cholesterol) into the cell. LDL binds to transmembrane receptors on the cell membrane. Adapter proteins allow clathrin to attach to the inner surface of the membrane. These protein complexes bend the membrane inward, creating a clathrin-coated vesicle inside the cell. The neck of the endocytic vesicle is pinched off from the membrane by a complex of the protein dynamin and other accessory proteins.
The endocytic vesicle fuses with an early endosome, and the LDL dissociates from the receptor proteins due to a lower pH environment. Empty receptor proteins are separated into transport vesicles to be re-inserted into the outer cell membrane. LDL remains in the endosome, which binds with a lysosome. The lysosome provides digestive enzymes that break up LDL into free cholesterol that can be used by the cell.
Roles of Receptor-Mediated Endocytosis
Receptor-mediated endocytosis is also used to regulate cell signaling. Sequestration is one of the primary ways to regulate signal receptors, and the process involves bringing receptors inside the cell using endocytosis. Some receptors are stored within vesicles until needed again, and some are degraded by proteolytic enzymes. Other signaling pathways require receptor-mediated endocytosis to allow signal transduction (i.e., passing the signal into the cell).&#160; There are also alternative pathways for endocytosis, of which caveolin is the most studied. Unlike clathrin, which binds to the surface of the bilayer, caveolin inserts itself into the lipid bilayer.
Use of Receptor-Based Endocytic Pathways by Pathogens
Some bacteria and viruses can invade host cells by hijacking the host&#39;s native receptors. The influenza virus can invade host cells using clathrin-mediated and other endocytic pathways. The virus binds to receptors on the cell surface, gaining access to the host cell and later escaping from the endosome.
Some pathogens release toxins that attach to host receptors to trick the cell into taking them inside. The bacterium Bacillus anthracis produces the toxin known as anthrax; this toxin can bind to the host cell&#39;s receptors, undergo endocytosis, and then escape the late endosome to cause clinical necrosis symptoms.

Receptor-mediated endocytosis is when bulk amounts of specific molecules are imported into a cell after binding to cell surface receptors. The molecules ...

Education

JoVE Core

Anatomy and Physiology

Unit 1

Cell Membrane Structure and Functions

KEY TERMS AND CONCEPTS

ligand binding in endocytosis

Receptor-mediated endocytosis is a selective way cells take in material from outside the cell. It begins when a ligand, or binding molecule, attaches to a receptor on the cell membrane. This interaction helps the cell capture specific substances instead of taking in everything around it.

After the ligand binds, the membrane folds inward and forms a small pocket. That pocket pinches off and brings the bound material into the cell. This process shows how receptor binding directs endocytosis and makes uptake more targeted.

Receptor-mediated endocytosis is an important part of cell function because it allows cells to control what enters. It is one example of how the cell membrane can recognize and move specific molecules across the boundary. The result is a precise form of endocytosis driven by receptor-ligand binding.

Ligand Binding in Endocytosis

what are membranes?

Membrane Layers in Cells and Tissues

Membranes are thin layers that help define cells and tissues. They act as boundaries and support important biological roles in the body. In cells, membranes help separate the inside of a cell from its surroundings. They also help control what moves in and out of the cell. In tissues, membranes can form covering layers that protect and support body structures. The video focuses on membranes as key parts of cell biology. It shows how these layers are organized and why they matter in living...

membrane proteins

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Membrane proteins help cells move materials across the cell membrane. They are part of the membrane structure and are closely linked to how cells function. Some membrane proteins act as channels or carriers. These proteins help selected substances pass through the membrane when direct movement through the lipid layer is not possible or is limited. Other membrane proteins help cells respond to signals. They can bind to molecules outside the cell and pass information inward. Membrane proteins...

membrane lipids

Membrane Lipids and Cell Membranes

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diffusion

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facilitated transport

Transport Across Cell Membranes

Transport across cell membranes helps cells move needed substances in and out. Facilitated transport is one way this happens. It uses membrane proteins to move materials that cannot pass easily through the lipid bilayer on their own. This process still follows the concentration gradient, so it moves from higher concentration to lower concentration. Because of that, it does not require cellular energy. The membrane proteins provide a path that helps the substance cross the membrane more...

non-gated ion channels

Ion Flow Through Open Channels

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osmosis

Osmosis and Water Balance

Osmosis is the movement of free water molecules through a semipermeable membrane. In this process, water moves from a region with a high concentration of free water molecules to a region with a lower concentration of free water molecules. The membrane allows water to pass, but it limits the diffusion of solutes dissolved in the water. Osmosis is a special case of diffusion. Diffusion moves material across membranes and within cells when molecules can spread out evenly. In a beaker with a...

tonicity in animals

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primary active transport

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secondary active transport

Coupled Solute Movement Across Membranes

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introduction to membrane traffic

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Receptor-mediated endocytosis is a selective way cells take in material from outside the cell. It begins when a ligand, or binding molecule, attaches to a receptor on the cell membrane. This interaction helps the cell capture specific substances instead of taking in everything around it. After the ligand binds, the membrane folds inward and forms a small pocket. That pocket pinches off and brings the bound material into the cell. This process shows how receptor binding directs endocytosis and...

key terms and concepts

Learn how receptor-mediated endocytosis works as ligands bind to membrane receptors and trigger selective uptake into the cell.

Ligand Binding in Endocytosis | JoVE K12

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BIO.5.D

Science concepts--biological structures, functions, and processes. The student knows that biological structures at multiple levels of organization perform specific functions and processes that affect life. The student is expected to:

Ligand Binding in Endocytosis

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