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Gangliosides
A ganglioside is a molecule composed of a glycosphingolipid (ceramide and oligosaccharide) with one or more sialic acids (e.g. N-acetylneuraminic acid, ''N''-acetylneuraminic acid, NANA) linked on the sugar chain. NeuNAc, an acetylated derivative of the carbohydrate sialic acid, makes the head groups of gangliosides anionic at pH 7, which distinguishes them from globosides. The name ''ganglioside'' was first applied by the German scientist Ernst Klenk in 1942 to lipids newly isolated from ganglion, ganglion cells of the brain. More than 60 gangliosides are known, which differ from each other mainly in the position and number of N-Acetylneuraminic acid, NANA residue (chemistry), residues. It is a component of the cell plasma membrane that modulates cell signal transduction events, and appears to concentrate in lipid rafts. Recently, gangliosides have been found to be highly important molecules in immunology. Natural and semisynthetic gangliosides are considered possible therapeut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexosaminidase A
Hexosaminidase (, ''beta-acetylaminodeoxyhexosidase'', ''N-acetyl-beta-D-hexosaminidase'', ''N-acetyl-beta-hexosaminidase'', ''N-acetyl hexosaminidase'', ''beta-hexosaminidase'', ''beta-acetylhexosaminidinase'', ''beta-D-N-acetylhexosaminidase'', ''beta-N-acetyl-D-hexosaminidase'', ''beta-N-acetylglucosaminidase'', ''hexosaminidase A'', ''N-acetylhexosaminidase'', ''beta-D-hexosaminidase'') is an enzyme involved in the hydrolysis of terminal N-acetyl-D-hexosamine residues in N-acetyl-β-D-hexosaminides. Elevated levels of hexosaminidase in blood and/or urine have been proposed as a biomarker of relapse in the treatment of alcoholism. Hereditary inability to form functional hexosaminidase enzymes are the cause of lipid storage disorders Tay–Sachs disease, Tay-Sachs disease and Sandhoff disease. Isozymes and genes Lysosomal A, B, and S isozymes Functional lysosome, lysosomal β-hexosaminidase enzymes are dimeric in structure. Three isozymes are produced through the combina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tay–Sachs Disease
Tay–Sachs disease is a genetic disorder that results in the destruction of nerve cells in the brain and spinal cord. The most common form is infantile Tay–Sachs disease, which becomes apparent around three to six months of age, with the baby losing the ability to turn over, sit, or crawl. This is then followed by seizures, hearing loss, and inability to move, with death usually occurring by the age of three to five. Less commonly, the disease may occur in later childhood or adulthood (juvenile or late-onset). These forms tend to be less severe, but the juvenile form typically results in death by age 15. Tay–Sachs disease is caused by a genetic mutation in the ''HEXA'' gene on chromosome 15, which codes form a subunit of the hexosaminidase enzyme known as hexosaminidase A. It is inherited from a person's parents in an autosomal recessive manner. The mutation disrupts the activity of the enzyme, which results in the build-up of the molecule GM2 ganglioside within cells, lea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ernst Klenk
Ernst Klenk (14 October 1896, Pfalzgrafenweiler – 29 December 1971, Cologne) was a German biochemist, known as a pioneer in research on biolipids, their metabolism, and diseases caused by biolipid disorders. Biography Klenk's father had a farm and a brewery in the Black Forest. However, Klenk did not want to take over his father's brewery and went to secondary school ( ''Gymnasium'') in Tübingen. After serving in WW I as a soldier from 1914 to January 1919, he studied chemistry at the University of Tübingen. At the University of Tübingen's ''Institut für Physiologische Chemie'' he in 1923, under the supervision of Percy Brigl (1885–1945), received his ''Promotion'' as Dr. rer. nat.; the doctoral dissertation is titled ''Verhalten von Dipeptiden und Elastin zu Phtalsäureanhydrid'' (reaction of dipeptides and elastin to phthalic anhydride). At the ''Institut für Physiologische Chemie'' Klenk was in 1923 appointed to the position of second assistant to the biochemist Hans T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycosphingolipid
Glycosphingolipids are a subtype of glycolipids containing the amino alcohol sphingosine. They may be considered as sphingolipids with an attached carbohydrate. Glycosphingolipids are a group of lipids (more specifically, sphingolipids) and are a part of the cell membrane. They consist of a hydrophobic ceramide part and a glycosidically bound carbohydrate part. This oligosaccharide content remains on the outside of the cell membrane where it is important for biological processes such as cell adhesion or cell–cell interactions. Glycosphingolipids play also important role in oncogenesis and ontogenesis. Classification In general, glycosphingolipids can be categorized into two groups: neutral glycosphingolipids (also called glycosphingolipids) and negatively charged glycosphingolipids. The latter can be distinguished again by means of the charge carrier. While in gangliosides sialic acids are found, sulfatides have a sulfate group. The structural similarity of most glycolipids is t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GM1 Ganglioside
GM1 (monosialotetrahexosylganglioside) the "prototype" ganglioside, is a member of the ganglio series of gangliosides which contain one sialic acid residue. GM1 has important physiological properties and impacts neuronal plasticity and repair mechanisms, and the release of neurotrophins in the brain. Besides its function in the physiology of the brain, GM1 acts as the site of binding for both cholera toxin and E. coli heat-labile enterotoxin (Traveller's diarrhea). GM1 and inherited disease Galactosidases are enzymes that break down GM1, and the failure to remove GM1 results in GM1 gangliosidosis. GM1 gangliosidosis are inherited disorders that progressively destroy neurons in the brain and spinal cord as GM1 accumulates. Without treatment, this results in developmental decline and muscle weakness, eventually leading to severe retardation and death. GM1 and acquired disease Antibodies to GM1 are increased in Guillain–Barré syndrome, dementia and lupus but their function is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cholera Toxin
Cholera toxin (also known as choleragen and sometimes abbreviated to CTX, Ctx or CT) is AB5 multimeric protein complex secreted by the bacterium ''Vibrio cholerae''. CTX is responsible for the massive, watery diarrhea characteristic of cholera infection. It is a member of the Heat-labile enterotoxin family. History Cholera toxin was discovered in 1959 by Indian microbiologist Sambhu Nath De. Structure The complete toxin is a hexamer made up of a single copy of the A subunit (part A, enzymatic, ), and five copies of the B subunit (part B, receptor binding, ), denoted as AB5. Subunit B binds while subunit A activates the G protein which activates adenylate cyclase. The three-dimensional structure of the toxin was determined using X-ray crystallography by Zhang ''et al.'' in 1995. The five B subunits—each weighing 11 kDa, form a five-membered ring. The A subunit which is 28 kDa, has two important segments. The A1 portion of the chain (CTA1) is a globular enzyme payload t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipid Raft
The plasma membranes of cells contain combinations of glycosphingolipids, cholesterol and protein receptors organised in glycolipoprotein lipid microdomains termed lipid rafts. Their existence in cellular membranes remains somewhat controversial. 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 trafficking, thereby regulating neurotransmission and receptor trafficking. Lipid rafts are more ordered and tightly packed than the surrounding bilayer, but float freely within the membrane bilayer. Although more common in the cell membrane, lipid rafts have also been reported in other parts of the cell, such as the Golgi apparatus and lysosome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GM2 (organic Compound)
In organic chemistry, GM2 is a type of ganglioside. G refers to ganglioside, the M is for monosialic (as in it has one sialic acid), and 2 refers to the fact that it was the second monosialic ganglioside discovered. It is associated with GM2 gangliosidoses such as Tay–Sachs disease. See also * Ganglioside GM2 activator protein GM2 ganglioside activator also known as GM2A is a protein which in humans is encoded by the ''GM2A'' gene. Function The protein encoded by this gene is a small glycolipid transport protein which acts as a substrate specific co-factor for the l ... Additional images Image:Sphingolipidoses.svg, Sphingolipidoses Image:Structure of GM1, GM2, GM3.png, Structures of GM1, GM2, GM3 gangliosides References External links * {{Sphingolipids Glycolipids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-acetylneuraminic Acid
''N''-Acetylneuraminic acid (Neu5Ac or NANA) is the predominant sialic acid found in human cells, and many mammalian cells. Other forms, such as N-Glycolylneuraminic acid, may also occur in cells. This residue is negatively charged at physiological pH and is found in complex glycans on mucins and glycoproteins found at the cell membrane. Neu5Ac residues are also found in glycolipids, known as gangliosides, a crucial component of neuronal membranes found in the brain. Along with involvement in preventing infections (mucus associated with mucous membranes—mouth, nose, GI, respiratory tract), Neu5Ac acts as a receptor for influenza viruses, allowing attachment to mucous cells via hemagglutinin (an early step in acquiring influenzavirus infection). In the biology of bacterial pathogens Neu5Ac is also important in the biology of a number of pathogenic and symbiotic bacteria as it can used either as a nutrient, providing both carbon and nitrogen to the bacteria, or in some pathogen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceramide
Ceramides are a family of waxy lipid molecules. A ceramide is composed of N-acetylsphingosine and a fatty acid. Ceramides are found in high concentrations within the cell membrane of eukaryotic cells, since they are component lipids that make up sphingomyelin, one of the major lipids in the lipid bilayer. Contrary to previous assumptions that ceramides and other sphingolipids found in cell membrane were purely supporting structural elements, ceramide can participate in a variety of cellular signaling: examples include regulating differentiation, proliferation, and programmed cell death (PCD) of cells. The word ''ceramide'' comes from the Latin ''cera'' (wax) and ''amide''. Ceramide is a component of vernix caseosa, the waxy or cheese-like white substance found coating the skin of newborn human infants. Pathways for ceramide synthesis There are three major pathways of ceramide generation. First, the sphingomyelinase pathway uses an enzyme to break down sphingomyelin in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gangliosidosis
Gangliosidosis contains different types of lipid storage disorders caused by the accumulation of lipids known as gangliosides. There are two distinct genetic causes of the disease. Both are autosomal recessive and affect males and females equally. Types * GM1 gangliosidoses - GM1 * GM2 gangliosidoses The GM2 gangliosidoses are a group of three related genetic disorders that result from a deficiency of the enzyme beta-hexosaminidase. This enzyme catalyzes the biodegradation of fatty acid derivatives known as gangliosides. The diseases are bett ... - GM2 See also * Sphingolipidoses#Overview References External links Autosomal recessive disorders Lipid storage disorders Rare diseases {{endocrine-disease-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lysosome
A lysosome () is a membrane-bound organelle found in many animal cells. They are spherical vesicles that contain hydrolytic enzymes that can break down many kinds of biomolecules. A lysosome has a specific composition, of both its membrane proteins, and its lumenal proteins. The lumen's pH (~4.5–5.0) is optimal for the enzymes involved in hydrolysis, analogous to the activity of the stomach. Besides degradation of polymers, the lysosome is involved in various cell processes, including secretion, plasma membrane repair, apoptosis, cell signaling, and energy metabolism. Lysosomes act as the waste disposal system of the cell by digesting used materials in the cytoplasm, from both inside and outside the cell. Material from outside the cell is taken up through endocytosis, while material from the inside of the cell is digested through autophagy. The sizes of the organelles vary greatly—the larger ones can be more than 10 times the size of the smaller ones. They were discov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
