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Encyclopedia > Lamellipodia
A GFP label of the actin cytoskeleton in a melanoma cell, showing a ruffled-edge lamellipodium, from Cell Biology at IMB Salzburg.
A GFP label of the actin cytoskeleton in a melanoma cell, showing a ruffled-edge lamellipodium, from Cell Biology at IMB Salzburg.

The lamellipodium (pl. Lamellipodia) is a cytoskeletal actin projection on the mobile edge of the cell. It is essentially a two-dimensional actin mesh that pulls the cell across a substrate (Alberts, et al, 2002). Within the lamellipodia are ribs of actin called microspikes, which, when they spread beyond the lamellipodium frontier, are called filopodia (Small, et all, 2002). The lamellipodium is born of actin nucleation in the plasma membrane of the cell (Alberts, et al, 2002) and is the primary area of actin incorperation or microfilament formation of the cell. Lamellipodia range from 1μm to 5μm in breadth and are approximately 0.2μm thick (Weed, et al, 2000). GFP ribbon diagram from PDB database The green fluorescent protein (GFP) is a protein from the jellyfish Aequorea victoria that fluoresces green when exposed to blue light. ... The cytoskeleton is a cellular scaffolding or skeleton contained, as all other organelles, within the cytoplasm. ... Actin (red) profilin (blue) complex. ... Cells in culture, stained for keratin (red) and DNA (green) The cell is the structural and functional unit of all living organisms, and are sometimes called the building blocks of life. ... Filopodia of macrophages. ... Bubbles in a soft drink each nucleate independently, responding to a decrease in pressure. ... 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. ... This article or section should be merged with actin Microfilaments or actin filaments are made up of two twisted monomeric actin subunits. ...


Lamellipodia are found primarily in very mobile cells, in particular the keratinocytes of fish and frogs, which are involved in the quick repair of wounds. These cells crawl at a very fast rate over epithelial surfaces, and a lamellipodium isolated from one of these cells can crawl freely about on its own. A lamellipodium can be separated from its cell by scratching across the cell with a pipette tip (Alberts, et al, 2002). The keratinocyte is the major cell type of the epidermis, making up about 90% of epidermal cells. ... Atlantic herring, Clupea harengus: the most abundant species of fish in the world. ... This is the current Article Improvement Drive collaboration! CAST YOUR VOTE for next weeks article For other uses, see Frog (disambiguation). ... Wound healing, or wound repair, is the bodys natural process of regenerating dermal and epidermal tissue. ... In zootomy, epithelium is a tissue composed of a layer of cells. ... Oxford Single-Channel Pipettes A pipette (often incorrectly spelled pipet) is a laboratory instrument used to transport a measured quantity of liquid. ...


Structurally, the plus ends of the microfilaments (localized actin monomers in an ATP-bound form) face the "seeking" edge of the cell, while the minus ends (localized actin monomers in an ADP-bound form) face the lamella behind (Cramer, 1997). This creates treadmilling throughout the lamellipodium, which aids in the retrograde flow of particles throughout (ibid.). Arp2/3 complexes are present at microfilament-microfilament junctions in lamellipodia, and help create the actin meshwork. Arp 2/3 can only join onto previously existing microfilaments, but once bound it creates a cite for the extension of new microfilaments, which creates branching (Weed, et al, 2000). Another molecule that is often found in polymerizing actin with Arp2/3 is cortactin, which appears to link tyrosine kinase signalling to cytoskeletal reorganization in the lamellipodium and its associated structures (ibid.). In chemistry, a monomer (from Greek mono one and meros part) is a small molecule that may become chemically bonded to other monomers to form a polymer. ... Adenosine 5-triphosphate (ATP) is the nucleotide known in biochemistry as the molecular currency of intracellular energy transfer; that is, ATP is able to store and transport chemical energy within cells. ... ADP is a three-letter abbreviation with multiple meanings, as described below: Association for the Development of Pakistan, a Boston-based non-profit organization Access database project, a file format of the Microsoft Access database program Adenosine diphosphate, a nucleotide Aéroports de Paris (see Air travel in France), airport... Tyrosine kinases are a subclass of protein kinase, see there for the principles of protein phosphorylation A tyrosine kinase (EC 2. ...


Rac and Cdc42 are two Rho-family GTPases which are normally cytosolic but can also be found in the cell membrane under certain conditions (Small, et al, 2002). When Cdc42 is activated, it can interact with Wiskott-Aldrich syndrome protein (WASp) family receptors, in particular N-WASp, which then activates Arp2/3. This stimulates actin branching and increases cell motility (Small, et al, 2002). Rac1 induces cortactin to localize to the cell membrane, where it simultaneously binds F-actin and Arp2/3. The result is a structural reorganization of the lamellipodium and ensuing cell motility (Weed, et al, 2000). 1. ... GTPases are a large family of enzymes that can bind and hydrolyze GTP. The GTP binding and hydrolysis takes place in the highly conserved G domain common to all GTPases. ... ÃThe cytosol (as opposed fatty cytoplasm, which also includes the organelles) is the internal fluid of the cell, and a large part of cell metabolism occurs here. ... Wiskott-Aldrich syndrome (WAS) is a rare X-linked recessive disease characterized by eczema, thrombocytopenia (low platelet counts), immune deficiency, and bloody diarrhea (due to the low platelet counts). ... WASP (an acronym for White Anglo-Saxon Protestant) is a term, sometimes derogatory, that denotes either an ethnic group, or the culture, customs, and heritage of the American elite Establishment. ... Motility is the ability to move spontaneously and independently. ...


References

  1. Alberts, Bruce, et al. Molecular Biology of the Cell. Fourth Edition. Garland Science, Taylor & Francis Group. New York, 2002: pgs 908, 931, 973-975.
  2. Cramer, Louise P. Molecular Mechanism of Actin-Dependant Pretrograde Flow in Lamellipodia of Motile Cells. Frontiers in Bioscience, 2, d260-270, June 1, 1997.
  3. Small, Victor J., et al. The lamellipodium: where motility begins. Trends in Cell Biology, Vol. 12 No. 3, March 2002: pgs. 112-120.
  4. Weed, Scott A., et al. Cortactin Localization to Sites of Actin Assembly in Lamellipodia Requires Interactions with F-Actin and the Arp2/3 Complex. The Journal of Cell Biology, Vol.151 No.1, October 2, 2000. pgs 29-40. Available Online
  5. Lamellipodia at the Department of Cell Biology at IMB Salzburg

 
 

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