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Glutamate Decarboxylase 2 (GAD2) is one of several forms of glutamic acid decarboxylase, identified as a main autoantigen in type II diabetes. The GAD2 enzyme is responsible for catalyzing the production of gamma-aminobutyric acid from L-glutamic acid. A pathogenic role for the GAD2 enzyme has been characterized in the human pancreas since it has been identified as an autoantibody and an autoreactive T cell target in type II diabetes. GAD2 gene may also have a role in the stiff man syndrome. In addition, GAD2 catalyzes the production of GABA.

NUDT3 is a 172 amino acid cytoplasmic protein which is a member of the nudix hydrolase family and DIPP subfamily. NUDT3 functions as a negative regulator of the ERK 1/2 pathway and hydrolyzes 5-phosphoribose 1-diphosphate. NUDT3 is a monomer which binds magnesium as a cofactor. In addition, NUDT3 is widely expressed but can be found at highest levels in the liver, pancreas, brain and heart.

ITPA enzyme catalyzes the pyrophosphohydrolysis of both ITP (inosine triphosphate) and dITP (deoxyinosine triphosphate) to IMP (inosine monophosphate) and diphosphate. IMP is exercised as a substrate for purine nucleotide pathways. IMP is phosphorylated to ITP, and ITPA mediates the concentration of ITP in the cell by changing ITP back to IMP. Defects in ITPA result in ITPA deficiency which is thought to be inherited and is characterized by an over-accumulation of ITP in erythocytes, leukocytes and fibroblasts.

Guanosine-3',5'-bis(diphosphate)-pyrophosphohydrolase MESH1 (HDDC3) contains an active site for ppGpp hydrolysis and a conserved His-Asp-box motif for Mn(2+) binding. In accordance with its structure, HDDC3 effectively catalyzes the hydrolysis of guanosine 3',5'-diphosphate (ppGpp) both in vitro and in vivo. In addition, HDDC3 suppresses SpoT-deficient lethality and RelA-induced delayed cell growth in bacteria.

M2 autoantigen is a key mark of antimitochondrial autoantibodies (AMA), a typical serological feature in patients suffering from primary biliary cirrhosis (PBC) which is a serious autoimmune liver disease accompanied by damage to intrahepatic bile ducts. Molecular definition of the M2 antigen has displayed it as no less than 3 separate target proteins. The M2 role is like the so-called E2 subunits (or dihydrolipoamide transferases) of different mitochondrial dehydrogenase complexes:
*pyruvate dehydrogenase complex.
*branched chain 2-oxo-acid dehydrogenase complex.
*2-oxoglutarate dehydrogenase complex.
Biochemically, these complexes catalyze the oxidative decarboxylation of various alpha-keto-acid substrates and systematically engage with a prosthetic lipoamide group; they are situated in the mitochondrial matrix in association with the inner membrane. The most well-known reactivity of AMA positive PBC sera is against PDC-E2. Some patients have AMA which reacts with PDC-E2 alone (95%), but most patients also show reactivity against OGDC-E2 (39-88%) and/or BCOADC-E2 (53-55%). Actually, patients can be found with reactivity only against OGDC-E2 and/or BCOADC-E2 and no PDC-E2 autoantibodies. These patients will be overlooked in assays based on natural source-derived, predominantly PDC-E2-containing M2 antigen preparations.

Methionine sulfoxide reductase A (MSRA) is a member of the MsrA Met sulfoxide reductase family. The MSRA enzyme has a vital function as a repair enzyme for proteins which have been inactivated by oxidation. MSRA catalyzes the reversible oxidation-reduction of methionine sulfoxide in proteins to methionine. The three substrates of the MSRA enzyme are peptide-L-methionine, thioredoxin disulfide, and H2O, while its 2 products are peptide-L-methionine (R)-S-oxide and thioredoxin. The MSRA protein is ubiquitous and extremely conserved. Human and animal studies have shown the ultimate levels of expression in kidney and nervous tissue.

PFKM is a regulatory glycolytic enzyme that converts fructose 6-phosphate and ATP into fructose 1,6-bisphosphate (through PFK-1), fructose 2,6-bisphosphate (through PFK-2) and ADP. Three phosphofructokinase isozymes exist in humans: muscle, liver and platelet. Mutations in PFKM gene have been related with glycogen storage disease type VII, also identified as Tarui disease.

Fumarylacetoacetate hydrolase domain-containing protein 1 (FAHD1) is a member of the FAH family. FAHD1 is considered to have hydrolase activity and it uses Magnesium and Calcium as cofactors. It seems quite likely that the metal binding sites are involved in an enzymatic activity connected to the catabolism of aromatic amino acids.

GSTK1 is involved in cellular detoxification. GSTK1 is localized to the peroxisome and catalyzes the conjugation of the thiol group of glutathione (GSH) to the electrophilic groups of a broad range of hydrophobic substrates, leading to an easier removal of the latter from the cells.

Thioredoxin reductase (TrxR/NTR), an enzyme belonging to the flavoprotein family of pyridine nucleotide-disulfide oxidoreductases. Thioredoxin reductase (TrxR), a component of the thioredoxin system, including thioredoxin (Trx) and NADPH, catalyzes the transfer of electrons from NADPH to Trx, acts as a reductant of disulfide-containing proteins and participates in the defense system against oxidative stresses.

GGCT is a member of the family of transferases, specifically the aminoacyltransferases. GGCT protein catalyzes the formation of 5-oxoproline from gamma-glutamyl dipeptides and takes an important part in glutathione homeostasis. GGCT induces release of cytochrome c from mitochondria with resultant induction of apoptosis.

Phospholipase A2 (PLA2) catalyzes the hydrolysis of the sn-2 position of membrane glycerophospholipids to liberate arachidonic acid (AA), a precursor of eicosanoids including prostaglandins and leukotrienes. The same reaction also produces lysophosholipids, which represent another class of lipid mediators.
The secretory PLA2 (sPLA2) family, in which 10 isozymes have been identified, consists of low molecular weight, Ca2+-requiring secretory enzymes that have been implicated in a number of biological processes, such as modification of eicosanoid generation, inflammation, and host defense.
This enzyme has been proposed to hydrolyze phosphatidylcholine (PC) in lipoproteins to liberate lyso- PC and free fatty acids in the arterial wall, thereby facilitating the accumulation of bioactive lipids and modified lipoproteins in atherosclerotic foci.
In mice, sPLA2 expression significantly influences HDL particle size and composition and demonstrate that an induction of sPLA2 is required for the decrease in plasma HDL cholesterol in response to inflammatory stimuli. Instillation of bacteria into the bronchi was associated with surfactant degradation and a decrease in large:small ratio of surfactant aggregates in rats.

Set 7/9 is a histone methyltransferase (HMTase) that transfers methyl groups to Lys4 of histone H3, in complex with S-adenosyl-L-methionine (AdoMet). The methylation of lysine residues of histones plays a critical role in the regulation of chromatin structure and gene expression.
Acetylation, phosphorylation and methylation of the amino-terminal tails of histone are thought to be involved in the regulation of chromatin structure and function. The enzymes identified in the methylation of specific lysine residue on histones belong to the SET family with just one exception. Set7/9, unlike most other SET proteins, is exclusively a mono-methylase.

Cathepsin-A (CTSA) is a protective protein which is crucial for both the activity of beta-galactosidase and neuraminidase, CTSA associates with these enzymes and exerts a protective function required for their stability and activity. The CTSA protein is also a carboxypeptidase and can deamidate tachykinins. CTSA is a component of the lysosomal multienzyme complex along with beta-galactosidase and sialidase Neu1. CTSA is a multicatalytic enzyme with deamidase and esterase in addition to carboxypeptidase activities.

Cytochrome b5 reductase 1 (CYB5R1) is a part of the flavoprotein pyridine nucleotide cytochrome reductase family. CYB5R1 is engaged in desaturation and elongation of fatty acids, cholesterol biosynthesis, drug metabolism, and, in erythrocyte, methemoglobin decrease.

HPRT1 has a main part in the generation of purine nucleotides through the purine salvage pathway. HPRT1 primarily functions to salvage purines from degraded DNA to renewed purine synthesis. Therefore, it performs as a catalyst in the reaction between guanine and phosphoribosyl pyrophosphate to form GMP.

Mitochondrial methylglutaconyl-CoA hydratase (AUH) is involved in the amino acid degradation pathway by catalyzing the conversion of 3-methylglutaconyl-CoA to 3-hydroxy-3-methylglutaryl-CoA and water. AUH Human is expressed as a single mRNA species of 1.8 kb, and translated as a 40kDa precursor protein which is consequently processed to a 32kDa mature form. AUH has a very low enoyl-CoA hydratase activity. The AUH protein binds to the AU-rich element (ARE), which is a common element found in the 3' UTR of rapidly decaying mRNA such as c-fos, c-myc and granulocyte/ macrophage colony stimulating factor. AU-rich elements are involved in directing RNA to rapid degradation and deadenylation. In addition, AUH is homologous to enol-CoA hydratase, which is an enzyme involved in fatty acid degradation, and has been shown to have intrinsic hydratase enzymatic activity. AUH is therefore a bifunctional chimera between RNA binding and metabolic enzyme activity.

Nudix Type Motif 4 (NUDT4) regulates the turnover of diphosphoinositol polyphosphates. The turnover of these high-energy diphosphoinositol polyphosphates exemplifies a molecular switching activity with significant regulatory consequences. Molecular switching by diphosphoinositol polyphosphates may be a factor in regulating intracellular trafficking.

The Casein kinase 2 (EC2.7.11.1) is a serine/threonine-selective protein kinasethat is a tetramer of two alpha subunits and two beta subunits. The alpha subunits have the catalytic kinase domain. Casein kinase 2 has been implicated in cell cyclecontrol, DNA repair, regulation of the circadian rhythmand other cellular processes.
Casein kinase 2 activity has been reported to be activated following Wnt signaling pathwayactivation. A Pertussis toxin-sensitive G proteinand Disheveled appear to be an intermediary between Wnt-mediated activation of the Frizzled receptor and activation of casein kinase 2.

LDHA catalyzes the conversion of L-lactate and NAD to pyruvate and NADH in the final step of anaerobic glycolysis. LDHA is localized primarily in muscle tissue and is part of the lactate dehydrogenase family. Mutations in LDHA have been linked to exertional myoglobinuria. LDH1 is decreased in essential thrombocythemia. LDHA is induced through a non-genomic pathway of estrogen action. Reduction in LDH-A activity results in stimulation of mitochondrial respiration and decrease of mitochondrial membrane potential.

Pin 1 is a peptidyl-prolyl cis/trans isomerase (PPIase) which interacts with NIMA and essential for cell cycle regulation Pin1 is nuclear PPIase containing a WW protein interaction domain, and is structurally and functionally related to Ess1/Ptf1, an essential protein in budding yeast. PPIase activity is necessary for Ess1/Pin1 function in yeast. Pin1 is thus an essential PPIase that regulates mitosis presumably by interacting with NIMA and attenuating its mitosis-promoting activity. Substrates of Pin1 include the mitotic regulators (Cdc25 phosphatase and NIMA, PLK I, Wee, and Myt1 kinases), several transcription factors like b-Catenin, c-Jun, and the tumor suppressor protein p53, and some specific proteins like the RNA Pol II, the cytoskeleton protein tau, and the G1/S protein Cyclin D1.

Alcohol dehydrogenase 1A (ADH1A) is a member of the alcohol dehydrogenase family. ADH1A has a key role in ethanol metabolism. ADH1A along with coenzyme NAD catalyzes the reversible conversion of organic alcohols to ketones or aldehydes. The physiologic function of ADH1A in the liver is the elimination of ethanol formed by microorganisms in the intestinal tract. ADH1A is monomorphic and predominant in fetal and infant livers, growing to be less active in gestation and only weakly active during adulthood.

Acid phosphatase, prostate (ACPP) is a non-specific tyrosine phosphatase, which dephosphorylates a varied number of substrates under acidic conditions (pH 4-6) including alkyl, aryl, and acyl orthophosphate monoesters and phosphorylated proteins. ACPP has lipid phosphatase activity and inactivates lysophosphatidic acid in seminal plasma.