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HEXA
Hexosaminidase A (alpha polypeptide), also known as HEXA, is an enzyme that in humans is encoded by the ''HEXA'' gene, located on the 15th chromosome. Hexosaminidase A and the cofactor GM2 activator protein catalyze the degradation of the GM2 gangliosides and other molecules containing terminal N-acetyl hexosamines. Hexosaminidase A is a heterodimer composed of an alpha subunit (this protein) and a beta subunit. The alpha subunit polypeptide is encoded by the ''HEXA'' gene while the beta subunit is encoded by the '' HEXB'' gene. Gene mutations in the gene encoding the beta subunit (HEXB) often result in Sandhoff disease; whereas, mutations in the gene encoding the alpha subunit (HEXA, this gene) decrease the hydrolysis of GM2 gangliosides, which is the main cause of Tay–Sachs disease. Function Even though the alpha and beta subunits of hexosaminidase A can both cleave GalNAc residues, only the alpha subunit is able to hydrolyze GM2 gangliosides. The alpha subunit con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tay–Sachs Disease
Tay–Sachs disease is an Genetic disorder, inherited fatal lysosomal storage disease 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 the age of three to six months of age, with the infant losing the ability to turn over, sit, or crawl. This is then followed by seizures, hearing loss, and paralysis, inability to move, with death usually occurring by the age of three to five. Less commonly, the disease may occur later in childhood, adolescence, or adulthood (juvenile or late-onset). These forms tend to be less severe, but the juvenile form typically results in death by the age of 15. Tay–Sachs disease is caused by a genetic mutation in the ''HEXA'' gene on chromosome 15, which codes a Protein subunit, subunit of the hexosaminidase enzyme known as hexosaminidase A. It is inherited in an autosomal recessive manner. The mutation disrupts the activity of the enzyme, whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HEXA Location
Hexosaminidase A (alpha polypeptide), also known as HEXA, is an enzyme that in humans is encoded by the ''HEXA'' gene, located on the 15th chromosome. Hexosaminidase A and the cofactor GM2 activator protein catalyze the degradation of the GM2 gangliosides and other molecules containing terminal N-acetyl hexosamines. Hexosaminidase A is a heterodimer composed of an alpha subunit (this protein) and a beta subunit. The alpha subunit polypeptide is encoded by the ''HEXA'' gene while the beta subunit is encoded by the ''HEXB'' gene. Gene mutations in the gene encoding the beta subunit (HEXB) often result in Sandhoff disease; whereas, mutations in the gene encoding the alpha subunit (HEXA, this gene) decrease the hydrolysis of GM2 gangliosides, which is the main cause of Tay–Sachs disease. Function Even though the alpha and beta subunits of hexosaminidase A can both cleave GalNAc residues, only the alpha subunit is able to hydrolyze GM2 gangliosides. The alpha subunit conta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexosaminidase
Hexosaminidase (, ''β-acetylaminodeoxyhexosidase'', ''N-acetyl-β-D-hexosaminidase'', ''N-acetyl-β-hexosaminidase'', ''N-acetyl hexosaminidase'', ''β-hexosaminidase'', ''β-acetylhexosaminidinase'', ''β-D-N-acetylhexosaminidase'', ''β-N-acetyl-D-hexosaminidase'', ''β-N-acetylglucosaminidase'', ''hexosaminidase A'', ''N-acetylhexosaminidase'', ''β-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 and Sandhoff disease. Isoenzymes and genes Lysosomal A, B, and S isoenzymes Functional lysosomal β-hexosaminidase enzymes are dimeric in structure. Three isoenzymes are produced through the combination of α and β subunits to f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HEXB
Beta-hexosaminidase subunit beta is an enzyme that in humans is encoded by the ''HEXB'' gene. Hexosaminidase B is the beta subunit of the lysosomal enzyme beta-hexosaminidase that, together with the cofactor GM2 activator protein, catalyzes the degradation of the ganglioside GM2, and other molecules containing terminal N-acetyl hexosamines. Beta-hexosaminidase is composed of two subunits, alpha and beta, which are encoded by separate genes. Both beta-hexosaminidase alpha and beta subunits are members of family 20 of glycosyl hydrolases. Mutations in the alpha or beta subunit genes lead to an accumulation of GM2 ganglioside in neurons and neurodegenerative disorders termed the GM2 gangliosidoses. Beta subunit gene mutations lead to Sandhoff disease (GM2-gangliosidosis type II). Structure Gene The ''HEXB'' gene lies on the chromosome location of 5q13.3 and consists of 14 exons, spanning 35-40Kb. Protein HEXB consists of 556 amino acid residues and weighs 63111Da. Fun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome 15 (human)
Chromosome 15 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 15 spans about 99.7 million base pairs (the building material of DNA) and represents between 3% and 3.5% of the total DNA in cells. Chromosome 15 is an acrocentric chromosome, with a very small short arm (the "p" arm, for "petite"), which contains few protein coding genes among its 19 million base pairs. It has a larger long arm (the "q" arm) that is gene rich, spanning about 83 million base pairs. The human leukocyte antigen gene for β2-microglobulin is found on chromosome 15, as well as the FBN1 gene, coding for both fibrillin-1 (a protein critical to the proper functioning of connective tissue), and asprosin (a small protein produced from part of the transcribed FBN1 gene mRNA), which is involved in fat metabolism. Genes Number of genes The following are some of the gene count estimates of human chromosome 15. Because researchers use different appr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GM2A
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 lysosomal enzyme β-hexosaminidase A. β-hexosaminidase A, together with GM2 ganglioside activator, catalyzes the degradation of the ganglioside GM2, and other molecules containing terminal N-acetyl hexosamines. GM2A is a lipid transfer protein that stimulates the enzymatic processing of gangliosides, and also T-cell activation through lipid presentation. This protein binds molecules of ganglioside GM2, extracts them from membranes, and presents them to beta-hexosaminidase A for cleavage of N-acetyl-D-galactosamine and conversion to GM3. It was identified as a member of ML domain family of proteins involved in innate immunity and lipid metabolism in the SMART database. Regulation In melanocytic cells GM2A gene expression may be reg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Codon
Genetic code is a set of rules used by living cells to translate information encoded within genetic material (DNA or RNA sequences of nucleotide triplets or codons) into proteins. Translation is accomplished by the ribosome, which links proteinogenic amino acids in an order specified by messenger RNA (mRNA), using transfer RNA (tRNA) molecules to carry amino acids and to read the mRNA three nucleotides at a time. The genetic code is highly similar among all organisms and can be expressed in a simple table with 64 entries. The codons specify which amino acid will be added next during protein biosynthesis. With some exceptions, a three-nucleotide codon in a nucleic acid sequence specifies a single amino acid. The vast majority of genes are encoded with a single scheme (see the RNA codon table). That scheme is often called the canonical or standard genetic code, or simply ''the'' genetic code, though variant codes (such as in mitochondria) exist. History Efforts to understan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proline
Proline (symbol Pro or P) is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group but is rather a secondary amine. The secondary amine nitrogen is in the protonated form (NH2+) under biological conditions, while the carboxyl group is in the deprotonated −COO− form. The "side chain" from the α carbon connects to the nitrogen forming a pyrrolidine loop, classifying it as a aliphatic amino acid. It is non-essential in humans, meaning the body can synthesize it from the non-essential amino acid L-glutamate. It is encoded by all the codons starting with CC (CCU, CCC, CCA, and CCG). Proline is the only proteinogenic amino acid which is a secondary amine, as the nitrogen atom is attached both to the α-carbon and to a chain of three carbons that together form a five-membered ring. History and etymology Proline was first isolated in 1900 by Richard Willstätter who obtained the amino a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glutamic Acid
Glutamic acid (symbol Glu or E; known as glutamate in its anionic form) is an α- amino acid that is used by almost all living beings in the biosynthesis of proteins. It is a non-essential nutrient for humans, meaning that the human body can synthesize enough for its use. It is also the most abundant excitatory neurotransmitter in the vertebrate nervous system. It serves as the precursor for the synthesis of the inhibitory gamma-aminobutyric acid (GABA) in GABAergic neurons. Its molecular formula is . Glutamic acid exists in two optically isomeric forms; the dextrorotatory -form is usually obtained by hydrolysis of gluten or from the waste waters of beet-sugar manufacture or by fermentation.Webster's Third New International Dictionary of the English Language Unabridged, Third Edition, 1971. Its molecular structure could be idealized as HOOC−CH()−()2−COOH, with two carboxyl groups −COOH and one amino group −. However, in the solid state and mildly acidic water s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serine
Serine (symbol Ser or S) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated − form under biological conditions), a carboxyl group (which is in the deprotonated − form under biological conditions), and a side chain consisting of a hydroxymethyl group, classifying it as a polar amino acid. It can be synthesized in the human body under normal physiological circumstances, making it a nonessential amino acid. It is encoded by the codons UCU, UCC, UCA, UCG, AGU and AGC. Occurrence This compound is one of the proteinogenic amino acids. Only the L- stereoisomer appears naturally in proteins. It is not essential to the human diet, since it is synthesized in the body from other metabolites, including glycine. Serine was first obtained from silk protein, a particularly rich source, in 1865 by Emil Cramer. Its name is derived from the Latin for silk, '' sericum''. Serine's structure was established in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycine
Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid. Glycine is one of the proteinogenic amino acids. It is encoded by all the codons starting with GG (GGU, GGC, GGA, GGG). Glycine disrupts the formation of alpha-helices in secondary protein structure. Its small side chain causes it to favor random coils instead. Glycine is also an inhibitory neurotransmitter – interference with its release within the spinal cord (such as during a '' Clostridium tetani'' infection) can cause spastic paralysis due to uninhibited muscle contraction. It is the only achiral proteinogenic amino acid. It can fit into both hydrophilic and hydrophobic environments, due to its minimal side chain of only one hydrogen atom. History and etymology Glycine was discovered in 1820 by French chemist Henri Braconnot when he hydrolyzed gelatin by boiling it with sulfuric acid. He originally called it "sugar of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arginine
Arginine is the amino acid with the formula (H2N)(HN)CN(H)(CH2)3CH(NH2)CO2H. The molecule features a guanidinium, guanidino group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO2−) and both the amino and guanidino groups are protonated, resulting in a cation. Only the -arginine (symbol Arg or R) enantiomer is found naturally. Arg residues are common components of proteins. It is Genetic code, encoded by the DNA codon table, codons CGU, CGC, CGA, CGG, AGA, and AGG. The guanidine group in arginine is the Precursor (chemistry), precursor for the biosynthesis of nitric oxide. Like all amino acids, it is a white, water-soluble solid. The one-letter symbol R was assigned to arginine for its phonetic similarity. History Arginine was first isolated in 1886 from Lupinus luteus, yellow lupin seedlings by the German chemist Ernst Schulze (chemist), Ernst Schulze and his assistant Ernst Steiger. He named it from the Greek ''árg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
