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G6PC
Glucose-6-phosphatase, catalytic subunit (glucose 6-phosphatase alpha) is an enzyme that in humans is encoded by the ''G6PC'' gene. Glucose-6-phosphatase is an integral membrane protein of the endoplasmic reticulum that catalyzes the hydrolysis of D-glucose 6-phosphate to D-glucose and orthophosphate. It is a key enzyme in glucose homeostasis, functioning in gluconeogenesis and glycogenolysis Glycogenolysis is the breakdown of glycogen (n) to glucose-1-phosphate and glycogen (n-1). Glycogen branches are catabolized by the sequential removal of glucose monomers via phosphorolysis, by the enzyme glycogen phosphorylase. Mechanis .... Defects in the enzyme cause glycogen storage disease type I (von Gierke disease). Interactive pathway map See also * G6PC2 * G6PC3 * glucose 6-phosphatase * glycogen storage disease type I References Further reading * * * * * * * * * * * * * * * * * * * {{refend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glucose 6-phosphatase
The enzyme glucose 6-phosphatase (EC 3.1.3.9, G6Pase; systematic name D-glucose-6-phosphate phosphohydrolase) catalyzes the hydrolysis of glucose 6-phosphate, resulting in the creation of a phosphate group and free glucose: : D-glucose 6-phosphate + H2O = D-glucose + phosphate During fasting, adequate levels of blood glucose are assured by glucose liberated from liver glycogen stores by glycogenolysis, as well as BY glucose generated by gluconeogenesis in both the liver, and, to a lesser extent, the kidneys. D-glucose 6-phosphate is the product of both these pathways and must be converted to glucose before it can be exported from the cell into blood by membrane-bound glucose transporters. Glucose 6-phosphatase is therefore principally expressed in the liver and kidney - while skeletal muscle collectively contain the most substantial glycogen reserve in the body, glucose cannot be mobilised from it as muscle cells do not produce glucose 6-phosphatase. Insulin inhibits hepa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G6PC3
Glucose-6-phosphatase 3, also known as glucose-6-phosphatase beta, is an enzyme that in humans is encoded by the ''G6PC3'' gene. Function This gene encodes the catalytic subunit of glucose 6-phosphatase (G6Pase). G6Pase is located in the endoplasmic reticulum (ER) and catalyzes the hydrolysis of glucose 6-phosphate to glucose and phosphate in the last step of the gluconeogenic and glycogenolytic pathways. Clinical significance Mutations in this gene result in autosomal recessive severe congenital neutropenia. G6PC3 deficiency results in a phenotypic continuum. At one end the affected individuals have only neutropenia and related complications but no other organ is affected. This is sometimes referred to as ''non-syndromic'' or ''isolated severe congenital neutropenia''. Most affected individuals have a ''classic form'' of the disease with severe congenital neutropenia and cardiovascular and/or urogenital abnormalities. Some individuals have ''severe G6PC3 deficiency'' (al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G6PC2
Glucose-6-phosphatase 2 is an enzyme that in humans is encoded by the ''G6PC2'' gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei .... Function This gene encodes an enzyme belonging to the glucose-6-phosphatase catalytic subunit family. These enzymes are part of a multicomponent integral membrane system that catalyzes the hydrolysis of glucose-6-phosphate, the terminal step in gluconeogenic and glycogenolytic pathways, allowing the release of glucose into the bloodstream. The family member encoded by this gene is found in pancreatic islets and does not exhibit phosphohydrolase activity, but it is a major target of cell-mediated autoimmunity in diabetes. Several alternatively spliced transcript variants of this gene have been described, but their biological validity has not b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycogen Storage Disease Type I
Glycogen storage disease type I (GSD I) is an inherited disease that prevents the liver from properly breaking down stored glycogen, which is necessary to maintain adequate blood sugar levels. GSD I is divided into two main types, GSD Ia and GSD Ib, which differ in cause, presentation, and treatment. There are also possibly rarer subtypes, the translocases for inorganic phosphate (GSD Ic) or glucose (GSD Id); however, a recent study suggests that the biochemical assays used to differentiate GSD Ic and GSD Id from GSD Ib are not reliable, and are therefore GSD Ib. GSD Ia is caused by a deficiency in the enzyme glucose-6-phosphatase; GSD Ib, a deficiency in the transport protein glucose-6-phosphate translocase. Because glycogenolysis is the principal metabolic mechanism by which the liver supplies glucose to the body during fasting, both deficiencies cause severe hypoglycemia and, over time, excess glycogen storage in the liver and (in some cases) in the kidneys. Because of the g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecules known as product (chemistry), products. Almost all metabolism, metabolic processes in the cell (biology), cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme, pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts include Ribozyme, catalytic RNA molecules, also called ribozymes. They are sometimes descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and non-coding genes. During gene expression (the synthesis of Gene product, RNA or protein from a gene), DNA is first transcription (biology), copied into RNA. RNA can be non-coding RNA, directly functional or be the intermediate protein biosynthesis, template for the synthesis of a protein. The transmission of genes to an organism's offspring, is the basis of the inheritance of phenotypic traits from one generation to the next. These genes make up different DNA sequences, together called a genotype, that is specific to every given individual, within the gene pool of the population (biology), population of a given species. The genotype, along with environmental and developmental factors, ultimately determines the phenotype ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Membrane Protein
Membrane proteins are common proteins that are part of, or interact with, biological membranes. Membrane proteins fall into several broad categories depending on their location. Integral membrane proteins are a permanent part of a cell membrane and can either penetrate the membrane (Transmembrane protein, transmembrane) or associate with one or the other side of a membrane (Integral monotopic protein, integral monotopic). Peripheral membrane proteins are transiently associated with the cell membrane. Membrane proteins are common, and medically important—about a third of all human proteins are membrane proteins, and these are targets for more than half of all drugs. Nonetheless, compared to other classes of proteins, determining membrane protein structures remains a challenge in large part due to the difficulty in establishing experimental conditions that can preserve the correct (Native state, native) Protein structure, conformation of the protein in isolation from its native ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gluconeogenesis
Gluconeogenesis (GNG) is a metabolic pathway that results in the biosynthesis of glucose from certain non-carbohydrate carbon substrates. It is a ubiquitous process, present in plants, animals, fungi, bacteria, and other microorganisms. In vertebrates, gluconeogenesis occurs mainly in the liver and, to a lesser extent, in the cortex of the kidneys. It is one of two primary mechanisms – the other being degradation of glycogen ( glycogenolysis) – used by humans and many other animals to maintain blood sugar levels, avoiding low levels (hypoglycemia). In ruminants, because dietary carbohydrates tend to be metabolized by rumen organisms, gluconeogenesis occurs regardless of fasting, low-carbohydrate diets, exercise, etc. In many other animals, the process occurs during periods of fasting, starvation, low-carbohydrate diets, or intense exercise. In humans, substrates for gluconeogenesis may come from any non-carbohydrate sources that can be converted to pyruvate or inter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycogenolysis
Glycogenolysis is the breakdown of glycogen (n) to glucose-1-phosphate and glycogen (n-1). Glycogen branches are catabolized by the sequential removal of glucose monomers via phosphorolysis, by the enzyme glycogen phosphorylase. Mechanism In the muscles, glycogenolysis begins due to the binding of cAMP to phosphorylate kinase, converting the latter to its active form so it can convert phosphorylase b to phosphorylase a, which is responsible for catalyzing the breakdown of glycogen. The overall reaction for the breakdown of glycogen to glucose-1-phosphate is: : glycogen(n residues) + Pi glycogen(n-1 residues) + glucose-1-phosphate Here, glycogen phosphorylase cleaves the bond linking a terminal glucose residue to a glycogen branch by substitution of a phosphoryl group for the α →4linkage. Glucose-1-phosphate is converted to glucose-6-phosphate (which often ends up in glycolysis) by the enzyme phosphoglucomutase. Glucose residues are phosphorolysed from bra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
