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GARS is an (alpha)2 dimer which is a member of the class II family of tRNA synthetases. GARS is a glycyl-tRNA synthetase, one of the aminoacyl-tRNA synthetases which charge tRNAs with their cognate amino acids. GARS catalyzes the attachment of glycine to tRNA(Gly). In addition, GARS is able to produce diadenosine tetraphosphate (Ap4A), which is a universal pleiotropic signaling molecule required for cell regulation pathways, by direct condensation of two ATPs. GARS has been demonstrated to be a target of autoantibodies in the human autoimmune diseases, polymyositis or dermatomyositis.

Hexokinases phosphorylate glucose to produce glucose-6-phosphate, thus committing glucose to the glycolytic pathway. Alternative splicing of Glucokinase results in three tissue-specific forms of glucokinase, one found in pancreatic islet beta cells and two found in liver. The protein localizes to the outer membrane of mitochondria. In contrast to other forms of hexokinase, HK4 is not inhibited by its product glucose-6-phosphate but remains active while glucose is abundant. Mutations in this gene have been associated with non-insulin dependent diabetes mellitus (NIDDM), maturity onset diabetes of the young, type 2 (MODY2) and persistent hyperinsulinemic hypoglycemia of infancy (PHHI).

GCK is an enzyme that expedite the formation of glucose-6-phosphate for glucose by phosphorylation. Humans and other vertebrates have GCK in the cells of the pancreas and liver. In both organs, the enzyme has an important role in carbohydrate metabolism regulation by sensing sugar levels and acting according to the change in glucose levels, that can rise after a meal or fall during fasting. Mutations in the gene that codes for this enzyme can cause hypoglycemia or diabetes.

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Glutathione peroxidase 3 (GPX3) is a member of the glutathione peroxidase family, which acts in the detoxification of hydrogen peroxide. GPX3 shields cells and enzymes from oxidative damage, by catalyzing the reduction of hydrogen peroxide, lipid peroxides and organic hydroperoxide, by glutathione. The GPX3 protein is one of only a few proteins known in higher vertebrates to contain selenocysteine, which occurs at the active site of glutathione peroxidase and is coded by the nonsense (stop) codon TGA.

Glutathione peroxidase 1 (GPX1) is a member of the glutathione peroxidase family, consisting of 8 identified glutathione peroxidases (Gpx1-8) in humans. Glutathione peroxidase serves in the detoxification of hydrogen peroxide, and is one of the most vital antioxidant enzymes in humans. The GPX1 is a component of the enzymatic antioxidant defense, preventing oxidative damage to DNA, proteins and lipids by detoxifying hydrogen and lipid peroxides which may contribute to prostate cancer development. GPX1 is one of only a small number of proteins known in higher vertebrates to contain selenocysteine, which occurs at the active site of glutathione peroxidase and is coded by the nonsense (stop) codon TGA. Furthermore, the GPX1 protein is characterized in a polyalanine sequence polymorphism in the N-terminal region, which includes 3 alleles with 5, 6 or 7 alanine (ALA) repeats in this sequence. The allele with 5 ALA repeats is significantly linked to breast cancer risk.

Glutathione peroxidase 2 (GPX2) is a member of the glutathione peroxidase family, consisting of 8 known glutathione peroxidases (Gpx1-8) in humans. Glutathione peroxidase functions in the detoxification of hydrogen peroxide, and is one of the most important antioxidant enzymes in humans. GPX2 may have a major role in protecting mammals from the toxicity of ingested organic hydroperoxides. GPX2 is one of only a few proteins known in higher vertebrates to contain selenocysteine, which appears at the active site of glutathione peroxidase and is coded by the nonsense (stop) codon TGA.

WWOX is a proapoptotic protein and a tumor suppressor protein. WWOX is found in all eukaryotes and involved in the regulation of a broad range of cellular functions such as protein degradation, transcription, and RNA splicing. WWOX functions synergistically with TP53/p53 to control genotoxic stress-induced cell death. WWOX takes part in tumor necrosis factor (TNF)-mediated cell death. Loss of WWOX expression is associated with pancreatobiliary cancers. Reduced expression levels of WWOX protein is associated with the pathogenesis of basal-like differentiation in breast cancer. Loss of WWOX expression is associated with extrahepatic cholangiocarcinoma. WWOX gene alteration is an early genetic alteration contributes to oral carcinogenesis. WWOX induces apoptosis and inhibits human hepatocellular carcinoma cell growth through a mechanism enhanced by JNK inhibition.

GGPS1 is PART of the prenyltransferase family. GGPS1 is widely expressed in testis, heart and skeletal muscle, GGPS1 is localized in the cytoplasm and catalyzes the formation of geranylgeranyl pyrophosphate, a precursor of geranylgeranylated proteins and carotenoids. GGPS1 is a significant enzyme that is responsible for the C20-prenylation of proteins and for the regulation of a nuclear hormone receptor.

Glycine-N-Acyltransferase-Like 2 (GLYATL2) is a part of the glycine N-acyltransferase family expressed mainly in salivary gland and trachea. GLYATL2 is a mitochondrial acyltransferase that transfers the acyl group to the N-terminus of glycine. GLYATL2 conjugates numerous substrates, like arachidonoyl-CoA and saturated medium and longchain acyl-CoAs ranging from chain-length C8:0-CoA to C18:0-CoA, to form a variety of N-acylglycines. GLYATL2 also shows a preference for monounsaturated fatty acid oleoyl-CoA (C18:1-CoA) as an acyl donor.

GLUL catalyzes the synthesis of glutamine from glutamate and ammonia. Glutamine is a major source of energy and that takes part in cell proliferation, inhibition of apoptosis, and cell signaling. GLUL is expressed during early fetal stages, and has a role in maintaining body pH by removing ammonia from circulation. Mutations in GLUL gene are related with congenital glutamine deficiency.

Aspartylglucosaminidase, also known as AGA, takes part in the catabolism of Nlinked oligosaccharides of glycoproteins. AGA is a protein coding gene which cleaves asparagine from N-acetylglucosamines in the lysosomal breakdown of glycoproteins.

Glucuronidase Beta (GUSB) is a lysosomal hydrolase which is taking part in the stepwise degradation of glucuronic acid-containing glycosaminoglycans and plays a significant role in the degradation of dermatan and keratin sulfates. GUSB is comprised of heparin sulfate, chondroitin sulfate and hyaluronan.

GPX7 is a member of the glutathione peroxidase family. Glutathione peroxidases (GPx) are a family of enzymes with peroxidase activity whose central biological role is to guard the organism from oxidative damage by reducing lipid hydroperoxides to their corresponding alcohols and to reduce free hydrogen peroxide to water.

UDP-Glucose Pyrophosphorylase 2, also known as UGP2 is an essential intermediary in mammalian carbohydrate inter conversions. UGP2 transfers a glucose moiety from glucose-1-phosphate to MgUTP and forms UDP-glucose and MgPPi. UDP-glucose is a direct precursor of glycogen in the liver and muscle tissue, moreover in lactating mammary gland it is converted to UDP-galactose which is next converted to lactose.

Phosphoglycerate mutase 2 (PGAM2) is a member of the phosphoglycerate mutase family. PGAM is a dimeric enzyme which contains in separate tissues, different proportions of a slow-migrating muscle (MM) isozyme, a fast-migrating brain (BB) isozyme, and a hybrid form (MB). PGAM (Phosphoglycerate mutase) catalyzes the reversible reaction of 3-phosphoglycerate (3-PGA) to 2-phosphoglycerate (2-PGA) in the glycolytic pathway. PGAM2 gene mutations cause muscle phosphoglycerate mutase efficiency, otherwise known as glycogen storage disease X.

GALM is a main enzyme of carbohydrate metabolism catalysing the translation of beta-D-galactose to alpha-D-galactose. GALM is needed for normal galactose metabolism by preserveing the equilibrium of alpha and beta anomers of galactose. GALM is required for the production of complex oligosaccharides.

GGH is a homodimeric protein which catalyzes the cleavage of the gamma-glutamyl chain of folylpoly-gamma-glutamyl substrates. GGH is a vital enzyme in folyl and antifolyl poly-gamma-glutamate metabolism and it has a significant part in the bioavailability of dietary pteroylpolyglutamates and in the metabolism of antifolates and pteroylpolyglutamates.

Glucokinase also known as GLK is a member of the bacterial glucokinase family. GLK is not highly significant in E.coli since glucoseis already transported into the cell through the PTS system as glucose 6-phosphate.

ENO3 is one of three enolase isoenzymes in mammals. The homodimer ENO3 is located in skeletal muscle cells of adults and has a part in converting phosphoglyceric acid to phosphenolpyruvic acid in the glycolytic pathway. Mutations in ENO3 gene is linked to metabolic myopathies which is caused by low stability of the enzyme.

Beta-galactosidase is a hydrolase enzyme that catalyzes the hydrolysis of Beta-galactosides into monosaccharides. Substrates of different Beta-galactosidases include ganglioside GM1, lactosylceramides, lactose, and various glycoproteins. Beta-galactosidase is produced In E. coli by activation of the lac operon as the lacZ gene.

Glycerol dehydrogenase (GldA) catalyzes the NAD-dependent oxidation of glycerol to dihydroxyacetone (glycerone). The GldA protein allows microorganisms to use glycerol as a source of carbon under anaerobic conditions. Furthermore, in E.coli GldA has an imperative role by regulating the intracellular level of dihydroxyacetone by catalyzing the reverse reaction, i.e. the conversion of dihydroxyacetone into glycerol. GldA possesses an extensive substrate specificity, due to its ability to oxidize 1,2-propanediol and to reduce glycolaldehyde, methylglyoxal and hydroxyacetone into ethylene glycol, lactaldehyde and 1,2-propanediol, respectively.

DCXR catalyzes the NADPH-dependent reduction of numerous pentoses, tetroses, trioses, alpha-dicarbonyl molecules and L-xylulose. DCXR takes part in the uronate cycle of glucose metabolism. DCXR participates in the water absorption and cellular osmoregulation in the proximal renal tubules by producing xylitol, an osmolyte, thus preventing osmolytic stress from occurring in the renal tubules.

L-threonine to glycine degradation consists of a two-step biochemical pathway which involvs the enzymes L-threonine dehydrogenase and 2-amino-3-ketobutyrate coenzyme A ligase. L-Threonine is initially converted into 2-amino-3-ketobutyrate by L-threonine dehydrogenase. Glycine C-Acetyltransferase (GCAT) is the 2nd enzyme in this pathway, which subsequently catalyzes the reaction between 2-amino-3-ketobutyrate and coenzyme A to form glycine and acetyl-CoA. The GCAT enzyme is regard as a class II pyridoxal-phosphate-dependent aminotransferase. GCAT is strongly expressed in the heart, brain, liver and pancreas. GCAT is also found in lung.

Glutaredoxin-2 (GrxB) is amember of the glutaredoxin family. Glutaredoxins are small redox enzymes of approximately 100 amino-acid residues which use glutathione as a cofactor. Glutaredoxins are oxidized by substrates, and reduced non-enzymatically by glutathione. GrxB is involved in reducing some disulfides in a coupled system with glutathione reductase. GrxB doesn’t act as hydrogen donor for ribonucleotide reductase.