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Encyclopedia > Vesicle (biology)

In cell biology, a vesicle is a relatively small and enclosed compartment, separated from the cytosol by at least one lipid bilayer. If there is only one lipid bilayer, they are called unilamellar vesicles; otherwise they are called multilamellar. Vesicles store, transport, or digest cellular products and waste. Cell biology (also called cellular biology or formerly cytology, from the Greek kytos, container) is an academic discipline that studies cells. ... The cytosol (cf. ... This fluid lipid bilayer cross section is made up entirely of phosphatidyl choline. ... This fluid lipid bilayer cross section is made up entirely of phosphatidyl choline. ... For the industrial process, see anaerobic digestion. ... 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... For other uses, see Waste (disambiguation). ...

Schematic showing the cytoplasm, with its components (or organelles), of a typical animal cell. Organelles: (1) nucleolus (2) nucleus (3) ribosome (4) vesicle (5) rough endoplasmic reticulum (6) Golgi apparatus (7) cytoskeleton (8) smooth endoplasmic reticulum (9) mitochondria (10) vacuole (11) cytosol (12) lysosome (13) centriole.
Schematic showing the cytoplasm, with its components (or organelles), of a typical animal cell. Organelles: (1) nucleolus (2) nucleus (3) ribosome (4) vesicle (5) rough endoplasmic reticulum (6) Golgi apparatus (7) cytoskeleton (8) smooth endoplasmic reticulum (9) mitochondria (10) vacuole (11) cytosol (12) lysosome (13) centriole.

This biomembrane enclosing the vesicle is similar to that of the plasma membrane. Because it is separated from the cytosol, the intravesicular environment can be made to be different from the cytosolic environment. Vesicles are a basic tool of the cell for organizing metabolism, transport, enzyme storage, as well as being chemical reaction chambers. Many vesicles are made in the Golgi apparatus, but also in the endoplasmic reticulum, or are made from parts of the plasma membrane. Image File history File links Biological_cell. ... Image File history File links Biological_cell. ... Organelles. ... Schematic of typical animal cell, showing subcellular components. ... The nucleolus is contained within the cell nucleus. ... HeLa cells stained for DNA with the Blue Hoechst dye. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ... The endoplasmic reticulum or ER is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae that is responsible for several specialized functions: Protein translation, folding, and transport of proteins to be used in the cell membrane (e. ... Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. ... The eukaryotic cytoskeleton. ... The endoplasmic reticulum or ER is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae that is responsible for several specialized functions: Protein translation, folding, and transport of proteins to be used in the cell membrane (e. ... Electron micrograph of a mitochondrion showing its mitochondrial matrix and membranes In cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed organelle that is found in most eukaryotic cells. ... Schematic of typical animal cell, showing subcellular components. ... The cytosol (cf. ... Organelles labeled at upper left. ... A centriole is a barrel shaped organelle[1] found in most eukaryotic cells, though absent in higher plants and fungi. ... 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. ... A few of the metabolic pathways in a cell. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. ... The endoplasmic reticulum or ER is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae that is responsible for several specialized functions: Protein translation, folding, and transport of proteins to be used in the cell membrane (e. ... 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. ...

Contents

Some types of vesicles

  • Lysosomes are membrane-bound digestive organelles that can digest macromolecules (break them down to small compounds) that were taken in from the outside of the cell by an endocytic vesicle.
  • Matrix vesicles are located within the extracellular space, or matrix. Using electron microscopy but working independently, they were discovered in 1967 by H. Clarke Anderson [1] and Ermanno Bonucci. [2] These cell-derived vesicles are specialized to initiate biomineralization of the matrix in a variety of tissues, including bone, cartilage, and dentin. During normal calcification, a major influx of calcium and phosphate ions into the cells accompanies cellular apoptosis (genetically determined self-destruction) and matrix vesicle formation. Calcium-loading also leads to formation of phosphatidylserine:calcium:phosphate complexes in the plasma membrane mediated in part by a protein called annexins. Matrix vesicles bud from the plasma membrane at sites of interaction with the extracellular matrix. Thus, matrix vesicles convey to the extracellular matrix calcium, phosphate, lipids and the annexins which act to nucleate mineral formation. These processes are precisely coordinated to bring about, at the proper place and time, mineralization of the tissue's matrix.

< math > Insertformulahere</math> The endoplasmic reticulum or ER is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae that is responsible for several specialized functions: Protein translation, folding, and transport of proteins to be used in the cell membrane (e. ... Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. ... In a neuron, synaptic vesicles, also called neurotransmitter vesicles, store the various neurotransmitters that are released during calcium-regulated exocytosis at the presynaptic terminal into the synaptic cleft of a synapse. ... In a synapse between two neurons, the cell that releases the neurotransmitter is referred to as the presynaptic cell. ... Neurons (also called nerve cells) are the primary cells of the nervous system. ... Chemical structure of D-aspartic acid, a common amino acid neurotransmitter. ... Organelles labeled at upper left. ... Schematic of typical animal cell, showing subcellular components. ... It has been suggested that Endocytic cycle be merged into this article or section. ... Illustration depicting extracellular matrix (basement membrane and interstitial matrix) in relation to epithelium, endothelium and connective tissue In biology, the extracellular matrix (ECM) is the extracellular part of animal tissue that usually provides structural support to the cells in addition to performing various other important functions. ... The electron microscope is a microscope that can magnify very small details with high resolving power due to the use of electrons rather than light to scatter off material, magnifying at levels up to 500,000 times. ... Biomineralisation (or biomineralization) is the process in which living organism produce minerals, often to harden or stiffen existing tissues in living organisms. ... This article is about the skeletal organs. ... Cartilage is a type of dense connective tissue. ... Parts of a tooth, including dentin Dentin (BE: dentine) is the substance between enamel (substance in the crown) or cementum (substance in the root) of a tooth and the pulp chamber. ... Dystrophic calcification is the mineralization of soft tissue without a systemic mineral imbalance. ... Phosphatidylserine is a phospholipid nutrient found in fish, green leafy vegetables, soybeans and rice, and is essential for the normal functioning of neuronal cell membranes. ... Annexin is a common name for a group of cellular proteins. ...


Vesicle formation and transport

Some vesicles are made when part of the membrane pinches off the endoplasmic reticulum or the Golgi complex. Others are made when an object outside of the cell is surrounded by the cell membrane.


Capturing cargo molecules

The assembly of a vesicle requires numerous coats to surround and bind to the proteins being transported. One family of coats are called adaptins. These bind to the coat vesicle (see below). They also trap various transmembrane receptor proteins, called cargo receptors, which in turn trap the cargo molecules.


Vesicle coat

The vesicle coat serves to sculpt the curvature of a donor membrane, and to select specific proteins as cargo. It selects cargo proteins by binding to sorting signals. In this way the vesicle coat clusters selected membrane cargo proteins into nascent vesicle buds. Protein targeting a. ...


There are three types of vesicle coats: clathrin, COPI and COPII. Clathrin coats are found on vesicles trafficking between the Golgi and plasma membrane, the Golgi and endosomes, and the plasma membrane and endosomes. COPI coated vesicles are responsible for retrograde transport from the Golgi to the ER, while COPII coated vesicles are responsible for anterograde transport from the ER to the Golgi. 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. ... COPI vesicles are retrograde transport vesicles. ... COPII vesicles transport proteins from the rough endoplasmic reticulum to the Golgi apparatus. ... In cell biology, the Golgi apparatus, Golgi body, Golgi complex, or dictyosome is an organelle found in most eukaryotic cells, including those of plants, animals, and fungi. ... 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. ... In biology an endosome is a membrane-bound compartment inside cells. ...


The clathrin coat is thought to assemble in response to regulatory G protein. A coatomer coat assembles and disassembles due to an ARF protein. 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. ... G-proteins, short for guanine nucleotide binding proteins, are a family of proteins involved in second messenger cascades. ... ARF could mean: Army Reserve Force, a division of the United States National Guard Acute rheumatic fever The ASEAN Regional Forum, part of the Association of Southeast Asian Nations Almost-Ready-To-Fly model aircraft ARF the GTP-binding protein Turkish mathematician Cahit Arf The vocalization of most any domestic...


Motor proteins

Motor proteins which change conformation and as a result move the vesicles along a set 'track'. The 'track' may consist of microtubules, for example. Motor proteins are a class of molecular motors that are able to move along the surface of a suitable substrate. ... Microtubules are one of the components of the cytoskeleton. ...


Vesicle docking

Surface markers called SNAREs identify the vesicle's cargo, and complementary SNAREs on the target membrane act to cause fusion of the vesicle and target membrane. Such v-SNARES are hypothesised to exist on the vesicle membrane, while the complementary ones on the target membrane are known as t-SNAREs. A kind of trap used in trapping. ...


Regulatory Rab proteins are thought to inspect the joining of the SNAREs. Rab protein is a regulatory GTP-binding protein, and controls the binding of these complementary SNAREs for a long enough time for the Rab protein to hydrolyse its bound GTP and lock the vesicle onto the membrane. Rab is a member of the Ras superfamily of GTPases. ...


Vesicle fusion

Fusion requires the two membranes to be brought within 1.5 nm of each other. For this to occur water must be displaced from the surface of the vesicle membrane. This is energetically unfavourable, and evidence suggests that the process requires ATP, GTP and acetyl-coA, fusion is also linked to budding, which is why the term budding and fusing arises.


Vesicles in receptor down-regulation

Membrane proteins serving as receptors are sometimes tagged for degregation by the attachment of ubiquitin. After arriving an endosome via the pathway described above, vesicles begin to form inside the endosome, taking with them the membrane proteins meant for degregation; When the endosome either matures to become a lysosome or is united with one, the vesicles are completely degregaded. Without this mechanism, only the extracellular part of the membrane proteins would reach the lumen of the lysosome, and only this part would be degraded[3]. Downregulation is the process by which a cell decreases the number of receptors to a given hormone or neurotransmitter to reduce its sensitivity to this molecule. ... 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. ... Ubiquitin is a very conserved small regulatory protein that is ubiquitous in eukaryotes. ... In biology an endosome is a membrane-bound compartment inside cells. ... Organelles labeled at upper left. ... Organelles labeled at upper left. ...


It is because of these vesicles that the endosome is sometimes known as a multivesicular body. However the pathway to their formation is not completely understood. Unlike the other vesicles described above, the outer surface of the vesicles is not in contact with the cytosol. The cytosol (cf. ...


References

  1. ^ Anderson, H. C. (1967), "Electronmicroscopic studies of induced cartilage development and calcification", Journal of Cell Biology, 35: 81-92
  2. ^ Bonucci, E. (1967), "Fine structure of early cartilage calcification", Journal of Ultrastructure Research, 20: 33-50
  3. ^ Katzmann, Odorizzi, Emr, Receptor downregulation and multivesicular-body sorting, Nature Reviews - Molecular cell biology, vol 3, Dec. 2002, 893
  • Bruce Alberts, et al (1994); Molecular Biology of the Cell; Third Edition

LOL


See also

Schematic of a micelle. ...

External links


  Results from FactBites:
 
vesicle - Search Results - MSN Encarta (164 words)
In cell biology, a vesicle is a relatively small and enclosed compartment, separated from the cytosol by at least one lipid bilayer.
Vesicle (biology), a relatively small and enclosed compartment within a cell; Vesicular texture, a small enclosed cavity found in some volcanic rock, such...
Vesicle In cellular biology, a vesicle is a relatively small and enclosed compartment, separated from the cytosol by at least one lipid bilayer.
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