FACTOID # 24: Looking for table makers? Head to Mississippi, with an overwhlemingly large number of employees in furniture manufacturing.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Membrane protein

A membrane protein is a protein molecule that is attached to, or associated with the membrane of a cell or an organelle. More than half of all proteins interact with membranes. Membrane proteins can be classified into two groups, based on the strength of their association with the membrane. A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... A biological membrane or biomembrane is a membrane which acts as a barrier within or around a cell. ... 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... Schematic of typical animal cell, showing subcellular components. ...

Contents

Main categories

Integral membrane proteins are permanently attached to the membrane. They can be defined as those proteins which require a detergent (such as SDS or Triton X-100) or some other apolar solvent to be displaced. They can be classified according to their relationship with the bilayer: An Integral Membrane Protein (IMP) is a protein molecule (or assembly of proteins) that is permanently attached to the biological membrane. ... Laundry detergents are just one of many possible uses for detergents Detergent is a compound, or a mixture of compounds, intended to assist cleaning. ... Sodium dodecyl sulfate (or sulphate) (SDS or NaDS) (C12H25NaO4S), also known as sodium lauryl sulfate (SLS), is an ionic surfactant that is used in household products such as toothpastes, shampoos, shaving foams and bubble baths for its thickening effect and its ability to create a lather. ...

  • Integral monotopic proteins are permanently attached to the membrane from only one side.

Peripheral membrane proteins are temporarily attached either to the lipid bilayer or to integral proteins by a combination of hydrophobic, electrostatic, and other non-covalent interactions. Peripheral proteins dissociate following treatment with a polar reagent, such as a solution with an elevated pH or high salt concentrations. A transmembrane protein is an integral membrane protein that spans from the internal to the external surface of the biological membrane or lipid bilayer in which it is embedded. ... A beta barrel is a protein fold containing a series of beta sheets, typically arranged in an antiparallel fashion. ... Side view of an α-helix of alanine residues in atomic detail. ... A biological membrane or biomembrane is a membrane which acts as a barrier within or around a cell. ... Mitochondria structure : 1) Inner membrane 2) Outer membrane 3) Crista 4) Matrix The outer membrane refers to the outside membranes of Gram-negative bacteria, the chloroplast, or the mitochondria. ... A beta barrel is a protein fold containing a series of beta sheets, typically arranged in an antiparallel fashion. ... Mitochondria structure : 1) Inner membrane 2) Outer membrane 3) Crista 4) Matrix The outer membrane refers to the outside membranes of Gram-negative bacteria, the chloroplast, or the mitochondria. ... Bacteria that are Gram-negative are not stained dark blue or violet by Gram staining, in contrast to Gram-positive bacteria. ... A cell wall is a fairly rigid layer surrounding a cell, located external to the cell membrane, that provides the cell with structural support, protection, and a filtering mechanism. ... Gram-positive bacteria are those that are stained dark blue or violet by gram staining, in contrast to Gram-negative bacteria, which are not affected by the stain. ... Mitochondria structure : 1) Inner membrane 2) Outer membrane 3) Crista 4) Matrix The outer membrane refers to the outside membranes of Gram-negative bacteria, the chloroplast, or the mitochondria. ... In cell biology, a mitochondrion is an organelle found in the cells of most eukaryotes. ... Chloroplasts are organelles found in plant cells and eukaryotic algae which conduct photosynthesis. ... Peripheral membrane proteins are proteins that adhere only temporarily to the biological membrane with which they are associated. ... This fluid lipid bilayer cross section is made up entirely of phosphatidyl choline. ... 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. ... Electrostatics is the branch of physics that deals with the force exerted by a static (i. ... The correct title of this article is . ...


Integral and peripheral proteins may be post-translationally modified, with added fatty acid or prenyl chains, or GPI (glycosylphosphatidylinositol), which may be anchored in the lipid bilayer. In chemistry, especially biochemistry, a fatty acid is a carboxylic acid often with a long unbranched aliphatic tail (chain), which is either saturated or unsaturated. ... Prenylation or isoprenylation or lipidation is the addition of hydrophobic molecules to a protein. ... Possible meanings: General paralysis of the insane Generic Pattern Implementation Genuine Progress Indicator Glass Packaging Institute Global Peatland Initiative Glycosylphosphatidylinositol Goldstein Psychonautic Institute This page concerning a three-letter acronym or abbreviation is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...

Further information: Integral membrane proteins, Transmembrane proteins, Peripheral membrane proteins


Classification of membrane proteins to integral and peripheral does not include some polypeptide toxins, such as colicin A or alpha-hemolysin, and certain proteins involved in apoptosis. These proteins are water-soluble but can aggregate and associate irreversibly with the lipid bilayer and form alpha-helical or beta-barrel transmembrane channels. An alternative classification is to divide all membrane proteins to integral and amphitropic[1] The amphitropic are proteins that can exist in two alternative states: a water-soluble and a lipid bilayer-bound, whereas integral proteins can be found only in the membrane-bound state. The amphitropic protein category includes water-soluble channel-forming polypeptide toxins, which associate irreversibly with membranes, but excludes peripheral proteins that interact with other membrane proteins rather than with lipid bilayer. Integral membrane protein of the transmembrane type An Integral Membrane Protein (IMP) is a protein molecule (or assembly of proteins) that in most cases spans the biological membrane with which it is associated (especially the plasma membrane) or which, in any case, is sufficiently embedded in the membrane to remain... A transmembrane protein is an integral membrane protein that spans from the internal to the external surface of the biological membrane or lipid bilayer in which it is embedded. ... Wikipedia does not yet have an article with this exact name. ... Bacteriocins are proteinaceous toxins produced by bacteria to inhibit the growth of similar bacterial strain(s). ... A section of mouse liver showing an apoptotic cell indicated by an arrow // Apoptosis is a process of deliberate life relinquishment by a cell in a multicellular organism. ... A beta barrel is a protein fold containing a series of beta sheets, typically arranged in an antiparallel fashion. ...


Membrane-bound peptides

There are also numerous membrane-associated peptides, some of which are nonribosomal peptides. They can form transmembrane channels (for example, gramicidins and peptaibols [2] [3]), travel across the membrane as ionophores (valinomycin and others), or associate with lipid bilayer surface, as daptomycin and other lipopeptides. These peptides are usually secreted. So, they probably should be classified as amphitropic, although some of them are poorly soluble in water and associate with membrane irreversibly. Nonribosomal peptides (NRP) are a class of secondary metabolites, usually produced by microorganisms like bacteria and fungi. ... The discontinuous diamer is seen showing the antiparallel hydrogen bonding between the amid hydrogens and carbonyl oxygens. ... An ionophore is a lipid-soluble molecule usually synthesized by microorganisms to transport ions across the lipid bilayer of the cell membrane. ... Valinomycin is a dodecadepsipeptide, that is it is made of twelve alternating amino acids to form a macrocyclic molecule. ... Daptomycin is a novel lipopeptide antibiotic used in the treatment of certain infections caused by Gram-positive organisms. ...


Further reading

  • Protein-lipid interactions (Ed. L.K. Tamm) Wiley, 2005.
  • Popot J-L. and Engelman D.M. 2000. Helical membrane protein folding, stability, and evolution. Annu. Rev. Biochem. 69: 881-922.
  • Bowie J.U. 2005. Solving the membrane protein folding problem. Nature 438: 581-589.
  • Cho, W. and Stahelin, R.V. 2005. Membrane-protein interactions in cell signaling and membrane trafficking. Annu. Rev. Biophys. Biomol. Struct. 34: 119–151.
  • Goni F.M. 2002. Non-permanent proteins in membranes: when proteins come as visitors. Mol. Membr. Biol. 19: 237-245.
  • Johnson J.E. and Cornell R.B. 1999. Amphitropic proteins: regulation by reversible membrane interactions. Mol. Membr. Biol. 16: 217-235.
  • Seaton B.A. and Roberts M.F. Peripheral membrane proteins. pp. 355-403. In Biological Membranes (Eds. K. Mertz and B.Roux), Birkhauser Boston, 1996.

See also

An Integral Membrane Protein (IMP) is a protein molecule (or assembly of proteins) that is permanently attached to the biological membrane. ... A transmembrane protein is a protein that spans the entire biological membrane. ... Peripheral membrane proteins are proteins that adhere only temporarily to the biological membrane with which they are associated. ... In biology, an ion pump is a transmembrane protein that moves ions across a plasma membrane against their concentration gradient. ... Carrier proteins are proteins that transport a particular substance in the blood or across the cell membrane. ... Ion channels are pore-forming proteins that help to establish and control the small voltage gradient that exists across the plasma membrane of all living cells (see cell potential) by allowing the flow of ions down their electrochemical gradient. ... 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. ... A Mu-opioid G protein-coupled receptor with its agonist Figure 1. ...

External links


  Results from FactBites:
 
Filtration and Membrane World: Protein Separations (930 words)
Soy protein concentrates are prepared by removing soluble sugars from defatted soy flakes or flours.
Another modified, "second-generation" soy protein concentrate of improved functionality is produced by successive pressure and cavitation, such as centrifugal homogenation at elevated temperatures and slightly alkaline pH, a high-NSI soy protein concentrate can be obtained from one that originally had a low NSI value.
It includes aqueous extraction of soluble proteins and carbohydrates from defatted soybean flakes or soy flour; separation of the insoluble residue, followed by precipitation of protein at mildly acidic conditions; separation and removal of the soluble carbohydrates, proteins, and salts; and washing and drying of the protein.
Membrane protein - Wikipedia, the free encyclopedia (575 words)
A membrane protein is a protein molecule that is attached to, or associated with the membrane of a cell or an organelle.
Membrane proteins can be classified into two groups, based on the strength of their association with the membrane.
Integral and peripheral proteins may be post-translationally modified, with added fatty acid or prenyl chains, or GPI (glycosylphosphatidylinositol), which may be anchored in the lipid bilayer.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m