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Lipid Raft
The cell membrane, plasma membranes of cells contain combinations of glycosphingolipids, cholesterol and protein Receptor (biochemistry), receptors organized in glycolipoprotein lipid microdomains termed lipid rafts. Their existence in cellular membranes remains controversial. Indeed, Kervin and Overduin imply that lipid rafts are misconstrued protein islands, which they propose form through a proteolipid code. Nonetheless, it has been proposed that they are specialized membrane microdomains which compartmentalize cellular processes by serving as organising centers for the assembly of signaling molecules, allowing a closer interaction of protein receptors and their effectors to promote kinetically favorable interactions necessary for the signal transduction. Lipid rafts influence membrane fluidity and membrane protein Protein targeting, trafficking, thereby regulating neurotransmission and receptor trafficking. Lipid rafts are more ordered and tightly packed than the surrounding bil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipid Raft Organisation Scheme
Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins Vitamin A, A, Vitamin D, D, Vitamin E, E and Vitamin K, K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing energy, lipid signaling, signaling, and acting as structural components of cell membranes. Lipids have applications in the Cosmetic industry, cosmetic and Food industry, food industries, and in nanotechnology. Lipids are broadly defined as Hydrophobe, hydrophobic or Amphiphile, amphiphilic small molecules; the amphiphilic nature of some lipids allows them to form structures such as vesicle (biology), vesicles, multilamellar/unilamellar liposomes, or membranes in an aqueous environment. Biological lipids originate entirely or in part from two distinct types of biochemical subunits or "building-blocks": :wikt:ketoacyl, ketoacyl and isoprene groups. Using this approach, lipids may be divided into eight catego ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphatidylcholine
Phosphatidylcholines (PC) are a class of phospholipids that incorporate choline as a headgroup. They are a major component of biological membranes and can easily be obtained from a variety of readily available sources, such as egg yolk or soybeans, from which they are mechanically or chemically extracted using hexane. They are also a member of the lecithin group of yellow-brownish fatty substances occurring in animal and plant tissues. Dipalmitoylphosphatidylcholine (lecithin) is a major component of the pulmonary surfactant, and is often used in the lecithin–sphingomyelin ratio to calculate fetal lung maturity. While phosphatidylcholines are found in all plant and animal cells, they are absent in the membranes of most bacteria, including ''Escherichia coli ''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Esch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metabolic reactions, DNA replication, Cell signaling, responding to stimuli, providing Cytoskeleton, structure to cells and Fibrous protein, organisms, and Intracellular transport, transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the Nucleic acid sequence, nucleotide sequence of their genes, and which usually results in protein folding into a specific Protein structure, 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called pep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phospholipid
Phospholipids are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typically have omega-3 fatty acids EPA and DHA integrated as part of the phospholipid molecule. The phosphate group can be modified with simple organic molecules such as choline, ethanolamine or serine. Phospholipids are a key component of all cell membranes. They can form lipid bilayers because of their amphiphilic characteristic. In eukaryotes, cell membranes also contain another class of lipid, sterol, interspersed among the phospholipids. The combination provides fluidity in two dimensions combined with mechanical strength against rupture. Purified phospholipids are produced commercially and have found applications in nanotechnology and materials science. The first phospholipid identified in 1847 as such in biological tissues w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphatidylinositol 4,5-bisphosphate
Phosphatidylinositol 4,5-bisphosphate or PtdIns(4,5)''P''2, also known simply as PIP2 or PI(4,5)P2, is a minor phospholipid component of cell membranes. PtdIns(4,5)''P''2 is enriched at the plasma membrane where it is a substrate for a number of important signaling proteins. PIP2 also forms lipid clusters that sort proteins. PIP2 is formed primarily by the type I phosphatidylinositol 4-phosphate 5-kinases from PI(4)P. In metazoans, PIP2 can also be formed by type II phosphatidylinositol 5-phosphate 4-kinases from PI(5)P. The fatty acids of PIP2 are variable in different species and tissues, but the most common fatty acids are stearic in position 1 and arachidonic in 2. Signaling pathways PIP2 is a part of many cellular signaling pathways, including PIP2 cycle, PI3K signalling, and PI5P metabolism. Recently, it has been found in the nucleus with unknown function. Functions Cytoskeleton dynamics near membranes PIP2 regulates the organization, polymerization, and bra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substrate Presentation
In molecular biology, substrate presentation is a biological process that activates a protein. The protein is sequestered away from its substrate and then activated by release and exposure to its substrate. A ''substrate'' is typically the substance on which an enzyme acts but can also be a protein surface to which a ligand binds. In the case of an interaction with an enzyme, the protein or organic substrate typically changes chemical form. Substrate presentation differs from allosteric regulation in that the enzyme need not change its conformation to begin catalysis. Substrate presentation is best described for domain partitioning at nanoscopic distances (<100 nm). Examples Amyloid precursor protein (APP) is cleaved by |
Palmitate Mediated Localization
Palmitate mediated localization is a biological process that trafficks a palmitoylated protein to ordered lipid domains. __TOC__ Biological function One function is thought to cluster proteins to increase the efficiency of protein-protein interactions and facilitate biological processes. In the opposite scenario palmitate mediated localization sequesters proteins away from a non-localized molecule. In theory, disruption of palmitate mediated localization then allows a transient interaction of two molecules through lipid mixing. In the case of an enzyme, palmitate can sequester an enzyme away from its substrate. Disruption of palmitate mediated localization then activates the enzyme by substrate presentation. Mechanism of sequestration Palmitate mediated localization is integral to spatial biology; in particular, lipid partitioning and the formation of lipid rafts The plasma membranes of cells contain combinations of glycosphingolipids, cholesterol and protein receptors o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palmitoylation
In molecular biology, palmitoylation is the covalent attachment of fatty acids, such as palmitic acid, to cysteine (''S''-palmitoylation) and less frequently to serine and threonine (''O''-palmitoylation) residues of proteins, which are typically membrane proteins. The precise function of palmitoylation depends on the particular protein being considered. Palmitoylation enhances the hydrophobicity of proteins and contributes to their membrane association. Palmitoylation also appears to play a significant role in subcellular trafficking of proteins between membrane compartments, as well as in modulating protein–protein interactions. In contrast to prenylation and myristoylation, palmitoylation is usually reversible (because the bond between palmitic acid and protein is often a thioester bond). The reverse reaction in mammalian cells is catalyzed by acyl-protein thioesterases (APTs) in the cytosol and palmitoyl protein thioesterases in lysosomes. Because palmitoylation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triton X-100
Triton X-100 (''n'') is a nonionic surfactant that has a hydrophilic polyethylene oxide chain (on average it has 9.5 ethylene oxide units) and an aromatic hydrocarbon lipophilic or hydrophobic group. The hydrocarbon group is a 4-( 1,1,3,3-tetramethylbutyl)- phenyl group. Triton X-100 is closely related to IGEPAL CA-630, which might differ from it mainly in having slightly shorter ethylene oxide chains. As a result, Triton X-100 is slightly more hydrophilic than Igepal CA-630 thus these two detergents may not be considered functionally interchangeable for most applications. Triton X-100 was originally a registered trademark of Rohm and Haas Co. It was subsequently purchased by Union Carbide and then acquired by Dow Chemical Company upon the acquisition of Union Carbide. Soon afterward (in 2009), Dow also acquired Rohm & Haas Co. Physical properties Undiluted Triton X-100 is a clear viscous fluid (less viscous than undiluted glycerol). Undiluted Triton X-100 has a viscosity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Detergent
A detergent is a surfactant or a mixture of surfactants with Cleanliness, cleansing properties when in Concentration, dilute Solution (chemistry), solutions. There are a large variety of detergents. A common family is the alkylbenzene sulfonates, which are soap-like compounds that are more soluble than soap in hard water, because the polar sulfonate is less likely than the polar carboxylate of soap to bind to calcium and other ions found in hard water. Definitions The word ''detergent'' is derived from the Latin adjective , from the verb , meaning to wipe or polish off. Detergent can be defined as a surfactant or a mixture of surfactants with cleansing properties when in Concentration, dilute Solution (chemistry), solutions. However, conventionally, detergent is used to mean synthetic cleaning compounds as opposed to ''soap'' (a salt of the natural fatty acid), even though soap is also a detergent in the true sense. In domestic contexts, the term ''detergent'' refers to househ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gibbs Free Energy
In thermodynamics, the Gibbs free energy (or Gibbs energy as the recommended name; symbol is a thermodynamic potential that can be used to calculate the maximum amount of Work (thermodynamics), work, other than Work (thermodynamics)#Pressure–volume work, pressure–volume work, that may be performed by a closed system, thermodynamically closed system at constant temperature and pressure. It also provides a necessary condition for processes such as chemical reactions that may occur under these conditions. The Gibbs free energy is expressed as G(p,T) = U + pV - TS = H - TS where: * U is the internal energy of the system * H is the enthalpy of the system * S is the entropy of the system * T is the temperature of the system * V is the volume of the system * p is the pressure of the system (which must be equal to that of the surroundings for mechanical equilibrium). The Gibbs free energy change (, measured in joules in International System of Units, SI) is the ''maximum'' amount of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid Disordered Phase
Liquid is a state of matter with a definite volume but no fixed shape. Liquids adapt to the shape of their container and are nearly incompressible, maintaining their volume even under pressure. The density of a liquid is usually close to that of a solid, and much higher than that of a gas. Therefore, liquid and solid are classified as condensed matter. Meanwhile, since both liquids and gases can flow, they are categorized as fluids. A liquid is composed of atoms or molecules held together by intermolecular bonds of intermediate strength. These forces allow the particles to move around one another while remaining closely packed. In contrast, solids have particles that are tightly bound by strong intermolecular forces, limiting their movement to small vibrations in fixed positions. Gases, on the other hand, consist of widely spaced, freely moving particles with only weak intermolecular forces. As temperature increases, the molecules in a liquid vibrate more intensely, causing t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
