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PMM2
Phosphomannomutase 2 is an enzyme that in humans is encoded by the ''PMM2'' gene. Function Phosphomannomutase 2 catalyzes the isomerization of mannose 6-phosphate to mannose 1-phosphate. Mannose 1-phosphate is a precursor to GDP-mannose necessary for the synthesis of dolichol-P-oligosaccharides. Mutations in the gene have been shown to cause defects in the protein glycosylation pathway which manifest as the congenital disorder of glycosylation A congenital disorder of glycosylation (previously called carbohydrate-deficient glycoprotein syndrome) is one of several rare inborn errors of metabolism in which glycosylation of a variety of tissue proteins and/or lipids is deficient or defe ... PMM2 deficiency. References Further reading * * * * * * * * * * * * * * * * * External links GeneReviews/NCBI/NIH/UW entry on Congenital Disorders of Glycosylation Overview GeneReviews/NIH/NCBI/UW entry on PMM2-CDG (CDG-Ia)Carbohydrate-Deficient Glycoprote ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Congenital Disorder Of Glycosylation
A congenital disorder of glycosylation (previously called carbohydrate-deficient glycoprotein syndrome) is one of several rare inborn errors of metabolism in which glycosylation of a variety of tissue proteins and/or lipids is deficient or defective. Congenital disorders of glycosylation are sometimes known as CDG syndromes. They often cause serious, sometimes fatal, malfunction of several different organ systems (especially the nervous system, muscles, and intestines) in affected infants. The most common sub-type is PMM2-CDG (formally known as CDG-Ia) where the genetic defect leads to the loss of phosphomannomutase 2 (PMM2), the enzyme responsible for the conversion of mannose-6-phosphate into mannose-1-phosphate. Presentation The specific problems produced differ according to the particular abnormal synthesis involved. Common manifestations include ataxia; seizures; retinopathy; liver disease; coagulopathies; failure to thrive (FTT); dysmorphic features (''e.g.,'' inverte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the 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 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 are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the react ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and 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 noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mannose 6-phosphate
Mannose-6-phosphate (M6P) is a molecule bound by lectin in the immune system. M6P is converted to fructose 6-phosphate by mannose phosphate isomerase. M6P is a key targeting signal for acid hydrolase precursor proteins that are destined for transport to lysosomes. The M6P tag is added to such proteins in the ''cis''-Golgi apparatus. Specifically, in a reaction involving uridine diphosphate (UDP) and ''N''-acetylglucosamine, the enzyme N-acetylglucosamine-1-phosphate transferase catalyzes the ''N''-linked glycosylation of asparagine residues with M6P. Once appropriately marked with the M6P targeting signal, these proteins are moved to the ''trans''-Golgi network. There, the M6P moiety is recognized and bound by mannose 6-phosphate receptor (MPR) proteins at pH 6.5–6.7. The M6P-tagged lysosomal enzymes are shipped to the late endosomes via vesicular transport. Enzyme replacement therapy (ERT) for several lysosomal storage diseases relies on this pathway to efficiently direct syn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mannose 1-phosphate
Mannose 1-phosphate is a molecule involved in glycosylation. See also * Congenital disorder of glycosylation A congenital disorder of glycosylation (previously called carbohydrate-deficient glycoprotein syndrome) is one of several rare inborn errors of metabolism in which glycosylation of a variety of tissue proteins and/or lipids is deficient or defect ... * Mannose-6-phosphate Organophosphates Monosaccharide derivatives {{organic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GDP-mannose
Guanosine diphosphate mannose or GDP-mannose is a nucleotide sugar that is a substrate for glycosyltransferase reactions in metabolism. This compound is a substrate for enzymes called mannosyltransferases. Known as donor of activated mannose in all glycolytic reactions, GDP-mannose is essential in eukaryotes. Biosynthesis GDP-mannose is produced from Guanosine triphosphate, GTP and mannose-6-phosphate by the enzyme mannose-1-phosphate guanylyltransferase. One of the enzymes from the family of nucleootidyl-transferases, GDP-Mannose Pyrophosphorylase (GDP-MP) is an pervasive enzyme found in bacteria, fungi, plants, and animals. References See also * Nucleoside * Nucleotide * Guanosine * Guanosine diphosphate Nucleotides Coenzymes {{biochem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
