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O-GlcNAc
''O''-GlcNAc (short for ''O''-linked GlcNAc or ''O''-linked β-''N''-acetylglucosamine) is a reversible enzymatic post-translational modification that is found on serine and threonine residues of nucleocytoplasmic proteins. The modification is characterized by a β-glycosidic bond between the hydroxyl group of serine or threonine side chains and ''N''-acetylglucosamine (GlcNAc). ''O''-GlcNAc differs from other forms of protein glycosylation: (i) ''O''-GlcNAc is not elongated or modified to form more complex glycan structures, (ii) ''O''-GlcNAc is almost exclusively found on nuclear and cytoplasmic proteins rather than membrane proteins and secretory proteins, and (iii) ''O''-GlcNAc is a highly dynamic modification that turns over more rapidly than the proteins which it modifies. ''O''-GlcNAc is conserved across metazoans. Due to the dynamic nature of ''O''-GlcNAc and its presence on serine and threonine residues, ''O''-GlcNAcylation is similar to protein phosphorylation in some r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
O-GlcNAc Clear Red
''O''-GlcNAc (short for ''O''-linked GlcNAc or ''O''-linked β-''N''-acetylglucosamine) is a reversible enzymatic post-translational modification that is found on serine and threonine residues of nucleocytoplasmic proteins. The modification is characterized by a β-glycosidic bond between the hydroxyl group of serine or threonine side chains and ''N''-acetylglucosamine (GlcNAc). ''O''-GlcNAc differs from other forms of protein glycosylation: (i) ''O''-GlcNAc is not elongated or modified to form more complex glycan structures, (ii) ''O''-GlcNAc is almost exclusively found on nuclear and cytoplasmic proteins rather than membrane proteins and secretory proteins, and (iii) ''O''-GlcNAc is a highly dynamic modification that turns over more rapidly than the proteins which it modifies. ''O''-GlcNAc is conserved across metazoans. Due to the dynamic nature of ''O''-GlcNAc and its presence on serine and threonine residues, ''O''-GlcNAcylation is similar to protein phosphorylation in some r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein O-GlcNAcase
Protein ''O''-GlcNAcase (, OGA, glycoside hydrolase ''O''-GlcNAcase, ''O''-GlcNAcase, BtGH84, ''O''-GlcNAc hydrolase) is an enzyme with systematic name (protein)-3-''O''-(''N''-acetyl-D-glucosaminyl)-L-serine/threonine ''N''-acetylglucosaminyl hydrolase. OGA is encoded by the ''OGA'' gene. This enzyme catalyses the removal of the ''O''-GlcNAc post-translational modification in the following chemical reaction: # rotein3-''O''-(''N''-acetyl-β-D-glucosaminyl)-L-serine + H2O roteinL-serine + ''N''-acetyl-D-glucosamine # rotein3-''O''-(''N''-acetyl-β-D-glucosaminyl)-L-threonine + H2O roteinL-threonine + ''N''-acetyl-D-glucosamine Nomenclature Other names include: * Nuclear cytoplasmic ''O''-GlcNAcase and acetyltransferase Isoforms The human OGA gene is capable of producing two different transcripts, each capable of encoding a different OGA isoform. The long isoform L-OGA, a bifunctional enzyme that possess a glycoside hydrolase activity and a pseudo histone-acetyl tran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein O-GlcNAc Transferase
Protein ''O''-GlcNAc transferase also known as OGT or O-linked N-acetylglucosaminyltransferase is an enzyme () that in humans is encoded by the ''OGT'' gene. OGT catalyzes the addition of the ''O''-GlcNAc post-translational modification to proteins. Nomenclature Other names include: *''O''-GlcNAc transferase * OGTase *''O''-linked ''N''-acetylglucosaminyltransferase * Uridine diphospho-''N''-acetylglucosamine:polypeptide β-''N''-acetylglucosaminyltransferase Systematic name: UDP-''N''-α-acetyl--glucosamine: rotein3-''O''-''N''-acetyl-β--glucosaminyl transferase Function Glycosyltransferase OGT catalyzes the addition of a single ''N''-acetylglucosamine through an ''O''-glycosidic linkage to serine or threonine and an ''S''-glycosidic linkage to cysteine residues of nucleocytoplasmic proteins. Since both phosphorylation and ''O''-GlcNAcylation compete for similar serine or threonine residues, the two processes may compete for sites, or they may alter the substrate s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-Acetylglucosamine
''N''-Acetylglucosamine (GlcNAc) is an amide derivative of the monosaccharide glucose. It is a secondary amide between glucosamine and acetic acid. It is significant in several biological systems. It is part of a biopolymer in the bacterial cell wall, which is built from alternating units of GlcNAc and ''N''-acetylmuramic acid (MurNAc), cross-linked with oligopeptides at the lactic acid residue of MurNAc. This layered structure is called peptidoglycan (formerly called murein). GlcNAc is the monomeric unit of the polymer chitin, which forms the exoskeletons of arthropods like insects and crustaceans. It is the main component of the radulas of mollusks, the beaks of cephalopods, and a major component of the cell walls of most fungi. Polymerized with glucuronic acid, it forms hyaluronan. GlcNAc has been reported to be an inhibitor of elastase release from human polymorphonuclear leukocytes (range 8–17% inhibition), however this is much weaker than the inhibition seen wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Post-translational Modification
Post-translational modification (PTM) is the covalent and generally enzymatic modification of proteins following protein biosynthesis. This process occurs in the endoplasmic reticulum and the golgi apparatus. Proteins are synthesized by ribosomes translating mRNA into polypeptide chains, which may then undergo PTM to form the mature protein product. PTMs are important components in cell signaling, as for example when prohormones are converted to hormones. Post-translational modifications can occur on the amino acid side chains or at the protein's C- or N- termini. They can extend the chemical repertoire of the 20 standard amino acids by modifying an existing functional group or introducing a new one such as phosphate. Phosphorylation is a highly effective mechanism for regulating the activity of enzymes and is the most common post-translational modification. Many eukaryotic and prokaryotic proteins also have carbohydrate molecules attached to them in a process called glycosyla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uridine Diphosphate N-acetylglucosamine
Uridine diphosphate ''N''-acetylglucosamine or UDP-GlcNAc is a nucleotide sugar and a coenzyme in metabolism. It is used by glycosyltransferases to transfer ''N''-acetylglucosamine residues to substrates. D-Glucosamine is made naturally in the form of glucosamine-6-phosphate, and is the biochemical precursor of all nitrogen-containing sugars. To be specific, glucosamine-6-phosphate is synthesized from fructose 6-phosphate and glutamine as the first step of the hexosamine biosynthesis pathway. The end-product of this pathway is UDP-GlcNAc, which is then used for making glycosaminoglycans, proteoglycans, and glycolipids. UDP-GlcNAc is extensively involved in intracellular signaling as a substrate for ''O''-linked ''N''-acetylglucosamine transferases (OGTs) to install the ''O''-GlcNAc post-translational modification in a wide range of species. It is also involved in nuclear pore formation and nuclear signalling. OGTs and OG-ases play an important role in the structure of the cyt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Phosphorylation
Protein phosphorylation is a reversible post-translational modification of proteins in which an amino acid residue is phosphorylated by a protein kinase by the addition of a covalently bound phosphate group. Phosphorylation alters the structural conformation of a protein, causing it to become either activated or deactivated, or otherwise modifying its function. Approximately 13000 human proteins have sites that are phosphorylated. The reverse reaction of phosphorylation is called dephosphorylation, and is catalyzed by protein phosphatases. Protein kinases and phosphatases work independently and in a balance to regulate the function of proteins. The amino acids most commonly phosphorylated are serine, threonine, tyrosine in eukaryotes, and also histidine in prokaryotes and plants (though it is now known to be common in humans). These phosphorylations play important and well-characterized roles in signaling pathways and metabolism. However, other amino acids can also be phosphory ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycosylation
Glycosylation is the reaction in which a carbohydrate (or ' glycan'), i.e. a glycosyl donor, is attached to a hydroxyl or other functional group of another molecule (a glycosyl acceptor) in order to form a glycoconjugate. In biology (but not always in chemistry), glycosylation usually refers to an enzyme-catalysed reaction, whereas glycation (also 'non-enzymatic glycation' and 'non-enzymatic glycosylation') may refer to a non-enzymatic reaction (though in practice, 'glycation' often refers more specifically to Maillard-type reactions). Glycosylation is a form of co-translational and post-translational modification. Glycans serve a variety of structural and functional roles in membrane and secreted proteins. The majority of proteins synthesized in the rough endoplasmic reticulum undergo glycosylation. Glycosylation is also present in the cytoplasm and nucleus as the ''O''-GlcNAc modification. Aglycosylation is a feature of engineered antibodies to bypass glycosylation. Five clas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha amino acids appear in the genetic code. Amino acids can be classified according to the locations of the core structural functional groups, as Alpha and beta carbon, alpha- , beta- , gamma- or delta- amino acids; other categories relate to Chemical polarity, polarity, ionization, and side chain group type (aliphatic, Open-chain compound, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling life ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cellular Stress Response
Cellular stress response is the wide range of molecular changes that cells undergo in response to environmental stressors, including extremes of temperature, exposure to toxins, and mechanical damage. Cellular stress responses can also be caused by some viral infections. The various processes involved in cellular stress responses serve the adaptive purpose of protecting a cell against unfavorable environmental conditions, both through short term mechanisms that minimize acute damage to the cell's overall integrity, and through longer term mechanisms which provide the cell a measure of resiliency against similar adverse conditions. General characteristics Cellular stress responses are primarily mediated through what are classified as ''stress proteins''. Stress proteins often are further subdivided into two general categories: those that only are activated by stress, or those that are involved both in stress responses and in normal cellular functioning. The essential character of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Cycle
The cell cycle, or cell-division cycle, is the series of events that take place in a cell that cause it to divide into two daughter cells. These events include the duplication of its DNA (DNA replication) and some of its organelles, and subsequently the partitioning of its cytoplasm, chromosomes and other components into two daughter cells in a process called cell division. In cells with nuclei ( eukaryotes, i.e., animal, plant, fungal, and protist cells), the cell cycle is divided into two main stages: interphase and the mitotic (M) phase (including mitosis and cytokinesis). During interphase, the cell grows, accumulating nutrients needed for mitosis, and replicates its DNA and some of its organelles. During the mitotic phase, the replicated chromosomes, organelles, and cytoplasm separate into two new daughter cells. To ensure the proper replication of cellular components and division, there are control mechanisms known as cell cycle checkpoints after each of the key steps ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apoptosis
Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes (morphology) and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, DNA fragmentation, and mRNA decay. The average adult human loses between 50 and 70 billion cells each day due to apoptosis. For an average human child between eight and fourteen years old, approximately twenty to thirty billion cells die per day. In contrast to necrosis, which is a form of traumatic cell death that results from acute cellular injury, apoptosis is a highly regulated and controlled process that confers advantages during an organism's life cycle. For example, the separation of fingers and toes in a developing human embryo occurs because cells between the digits undergo apoptosis. Unlike necrosis, apoptosis produces cell fragments called apoptotic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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