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Encyclopedia > Endocytosis

Endocytosis (IPA: [ɛndəʊsaɪˈtəʊsɪs]) is a process whereby cells absorb material (molecules such as proteins) from the outside by engulfing it with their cell membrane. It is used by all cells of the body because most substances important to them are large polar molecules, and thus cannot pass through the hydrophobic plasma membrane. The function of endocytosis is the opposite of exocytosis. Articles with similar titles include the NATO phonetic alphabet, which has also informally been called the “International Phonetic Alphabet”. For information on how to read IPA transcriptions of English words, see IPA chart for English. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... In science, a molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. ... Look up cell membrane in Wiktionary, the free dictionary. ... Polar may refer to: Polsk Ost med KATING WAPOOOOW CHING CHING WOWOWOWOW/Gling, Oink oink. ... In chemistry, hydrophobic or lipophilic species, or hydrophobes, tend to be electrically neutral and nonpolar, and thus prefer other neutral and nonpolar solvents or molecular environments. ... Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ... Neuron A (transmitting) to neuron B (receiving) 1. ...

Contents

Types

different forms of Endocytosis
different forms of Endocytosis

The absorption of material from the outside environment of the cell is commonly divided into two processes: phagocytosis and pinocytosis. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Steps of a macrophage ingesting a pathogen: a. ... Pinocytosis or cell drinking is one of three forms of endocytosis, a cellular process that is used to take up smaller particles in cell by splitting in small particles , and forms vesicles which then merge with lysosomes to hydrolyze (hydrolytic enyzmes) to break down the particles. ...

  • Phagocytosis (literally, cell-eating) is the process by which cells ingest large objects, such as cells which have undergone apoptosis, bacteria, or viruses. The membrane folds around the object, and the object is sealed off into a large vacuole known as a phagosome.
  • Pinocytosis (literally, cell-drinking) is a synonym for endocytosis. This process is concerned with the uptake of solutes and single molecules such as proteins.
  • Receptor-mediated endocytosis is a more specific active event where the cytoplasm membrane folds inward to form coated pits. These inward budding vesicles bud to form cytoplasmic vesicles.

A section of mouse liver showing an apoptotic cell indicated by an arrow Apoptosis (pronounced apo tō sis) is a process of suicide by a cell in a multicellular organism. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... This article is about biological infectious particles. ... Schematic of typical animal cell, showing subcellular components. ... In cell biology, a vacuole formed around a particle absorbed by phagocytosis. ... A substance is soluble in a fluid if it dissolves in the fluid. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ...

Endocytosis pathways

There are three types of endocytosis: namely, macropinocytosis, clathrin-mediated endocytosis, and caveolar endocytosis. Clathrin is a protein that is the major constituent of the coat of the coated pits and coated vesicles formed during endocytosis of materials at the surface of cells. ...

  • Macropinocytosis is the invagination of the cell membrane to form a pocket which then pinches off into the cell to form a vesicle filled with extracellular fluid (and molecules within it). The filling of the pocket occurs in a non-specific manner. The vesicle then travels into the cytosol and fuses with other vesicles such as endosomes and lysosomes.
  • Clathrin-mediated endocytosis is the specific uptake of large extracellular molecules such as proteins, membrane localized receptors and ion-channels. These receptors are associated with the cytosolic protein clathrin which initiates the formation of a vesicle by forming a crystalline coat on the inner surface of the cell's membrane.
  • Caveolae consist of the protein caveolin-1 with a bilayer enriched in cholesterol and glycosphingolipids. Caveolae are flask shaped pits in the membrane that resemble the shape of a cave (hence the name caveolae). Uptake of extracellular molecules are also believed to be specifically mediated via receptors in caveolae.

Look up cell membrane in Wiktionary, the free dictionary. ... In cell biology, a vesicle is a relatively small and enclosed compartment, separated from the cytosol by at least one lipid bilayer. ... The cytosol (cf. ... In biology an endosome is an endocytotic vesicle derived from the plasma membrane. ... Lysosomes are organelles in eukaryotic cells that contain digestive enzymes to digest macromolecules. ... In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific molecule (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. ... This article is about the electrically charged particle. ... In biology, caveolae (Latin for little caves) are small invaginations of the plasma membrane in many cell types, especially in endothelial cells. ... Cholesterol is a sterol (a combination steroid and alcohol), a lipid found in the cell membranes of all body tissues, and is transported in the blood plasma of all animals. ... In science, a molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. ...

Clathrin-mediated endocytosis

The major route for endocytosis in most cells, and the best understood, is that mediated by the molecule clathrin. This large protein assists in the formation of a coated pit on the inner surface of the plasma membrane of the cell. This pit then buds into the cell to form a coated vesicle in the cytoplasm of the cell. In so doing, it brings into the cell not only a small area of the surface of the cell but also a small volume of fluid from outside the cell. Clathrin is a protein that is the major constituent of the coat of the coated pits and coated vesicles formed during endocytosis of materials at the surface of cells. ... Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ...


Vesicles selectively concentrate and exclude certain proteins during formation and are not representative of the membrane as a whole. AP2 adaptors are multisubunit complexes that performs this function at the plasma membrane. The best understood receptors which are found concentrated in coated vesicles of mammalian cells are the LDL receptor (which removes LDL from the blood circulation), the transferrin receptor (which brings ferric ions bound by transferrin into the cell) and certain hormone receptors (such as that for EGF). There are very few or no other articles that link to this one. ... Brown and Goldstein won a Nobel Prize for their identification of the Low Density Lipoprotein (LDL) receptor 30 years ago whilst they were studying the disease familiar hypercholesterolaemia. ... Low-density lipoprotein (LDL) refers to a class and range of lipoprotein particles, varying somewhat in their size and contents, which carry cholesterol in the blood and around the body, for use by various cells. ... Transferrin is a plasma protein for iron ion delivery. ... Epidermal Growth Factor or EGF is a 6045 Da protein with 53 amino acid residues and three intramolecular disulfide bonds. ...


At any one moment, about 2% of the plasma membrane of a fibroblast is made up of coated pits. As a coated pit has a life of about a minute before it buds into the cell, a fibroblast takes up its surface by this route about once every 50 minutes. Coated vesicles formed from the plasma membrane have a diameter of about 100nm and a life time measured in a few seconds. Once the coat has been shed, the remaining vesicle fuses with endosomes and proceeds down the endocytic pathway. The actual budding-in process, whereby a pit is converted to a vesicle, is carried out by clathrin assisted by a set of cytoplasmic proteins which includes dynamin and adaptors such as adaptin. In biology an endosome is an endocytotic vesicle derived from the plasma membrane. ... Dynamin is a GTPase thought to be responsible for endocytosis in the eukaryotic cell, and is involved in vesicle (biology) trafficking both at the cell surface (particularly caveolae internalization) as well as at the Golgi (1)(2)(4). ... Adaptin is a protein mediating the formation of clathrin-coated pits, through interaction with membrane-bound receptors. ...


Coated pits and vesicles were first seen in thin sections of tissue in the electron microscope by Thomas Roth and Keith Porter in 1964. The importance of them for the clearance of LDL from blood was discovered by R. G Anderson, Michael S. Brown and Joseph L. Goldstein in 1976. Coated vesicles were first purified by Barbara Pearse, who discovered the clathrin coat molecule, also in 1976. Dr. Michael S. Brown (b. ... Joseph L. Goldstein (b. ... Barbara Pearse (born March 24, 1948 in Wraysbury, England) is a British biological scientist and Fellow of the Royal Society. ...


See also

Neuron A (transmitting) to neuron B (receiving) 1. ...

External links


  Results from FactBites:
 
Endocytosis - Specialized phagocytic cells engulf large particles (1061 words)
During endocytosis, the plasma membrane of the cell forms a pocket around the material to be internalized.
There are two main types of endocytosis that are distinguished by the size of the vesicle formed and the cellular machinery involved.
Receptor-mediated endocytosis was discovered by Michael Brown and Joseph Goldstein, who were investigating the internalization of cholesterol by cells from the bloodstream.
Endocytosis - Wikipedia, the free encyclopedia (347 words)
Endocytosis is a process whereby cells absorb material (molecules such as proteins) from outside by engulfing it with their cell membrane.
It is used by all cells of the body because most substances important to them are polar and consist of big molecules, and thus cannot pass through the hydrophobic plasma membrane.
Endocytosis is the opposite of exocytosis, and always involves the formation of a vesicle from part of the cell membrane.
  More results at FactBites »

 
 

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