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HECT and RLD Domain Containing E3 Ubiquitin Protein Ligase 5 (HERC5) is a member of the HERC family of ubiquitin ligases, found in a cluster of HERC family genes on chromosome 4. HERC5 is a protein with a HECT domain and 5 RCC1 repeats. The HERC5 protein localizes to the cytoplasm and perinuclear region and serves as an INF-induced E3 protein ligase that mediates ISGylation of protein targets. HERC5 exhibits antiviral activity towards HIV-1, influenza A virus and human papillomavirus. HERC5 is a major E3 ligase for ISG15 conjugation. HERC5 also serves as a positive regulator of innate antiviral response in cells induced by INF. Pro-inflammatory cytokines upregulate HERC5 in endothelial cells. HERC5 is physically connected with polyribosomes, broadly modifies recently synthesized proteins in a cotranslational fashion.

DCTPP1, also known as dCTP pyrophosphatase 1, contains an epilepsy-associated repeat (EAR) domain that is predicted to participate in protein-protein interactions, most likely involved in ligand recognition. This protein functions to hydrolyze abnormal nucleotide triphosphates (NTPs) in cancer cells that, if unregulated, could be incorporated into nascent DNA or RNA.

Aminoacyl-tRNA synthetases are a class of enzymes which charge tRNAs with their cognate amino acids. Asparaginyl-tRNA synthetase (NARS) is localized to the cytoplasm and is a member of the class II family of tRNA synthetases. The N-terminal domain characterizes the signature sequence for the eukaryotic asparaginyl-tRNA synthetases.

Erythrocyte acylphosphatase (ACYP1) is a cytosolic enzyme which catalyzes the hydrolysis of the carboxyl-phosphate bond of acylphosphates. There are two acylphophatase isoenzymes: ACYP1 and ACYP2. These isoenzymes share 60% homology and have the same substrate specificity, even though ACYP1 has a higher catalytic activity than ACYP2.

Hexokinases phosphorylate glucose to produce glucose-6-phosphate, thus committing glucose to the glycolytic pathway. HK3 encodes hexokinase 3. Similar to hexokinases 1 and 2, this allosteric enzyme is inhibited by its product glucose-6-phosphate. Hexokinase3 lacks the hydrophobic N-terminal sequence critical for targeting to mitochondria. Hexpkinase3 may have anabolic functions, providing H6P for glycogen or lipid synthesis.

Ornithine Aminotransferase is a mitochondrial enzyme which is an important factor that converts arginine and ornithine into the major excitatory and inhibitory neurotransmitters glutamate and GABA. Ornithine Aminotransferase mutations result in a deficiency that cause the autosomal recessive eye disease Gyrate Atrophy.

Beta-galactosidase or GLB1 is a B-galactosidase found in the lysosome. This enzyme hydrolyzes the finale B-galactose from the precursors ganglioside & keratin sulfate. GLB1 has a crucial part in the creation of elastogenesis (extracellular elastic fibers) and connective tissue development. This enzyme is similar to elastin-binding protein which is a key part in non-integrin cell surface receptor. In cells that extort elastin GLB1 is linked to tropoelastin intracellularly and act as recycling molecular chaperone.

AHCY is an enzyme that catalyzes the reversible hydrolysis of S-adenosylhomocysteine (AdoHcy) to adenosine (Ado) and L-homocysteine (Hcy). AHCY controls the intracellular S-adenosylhomocysteine (SAH) concentration that is crucial for transmethylation reactions. AHCY deficiency causes hypermethioninemia.

PGAM1 is part of the phosphoglycerate mutase family. PGAM1 is an essential component of glucose and 2,3-BPGA (2,3-bisphosphoglycerate) metabolism and catalyzes the reversible reaction of 3-phosphoglycerate (3-PGA) to 2-phosphoglycerate (2-PGA) in the glycolytic pathway. PGAM1 is a dimeric enzyme containing, in different tissues, different proportions of a slow-migrating muscle (MM) isozyme, a fast-migrating brain (BB) isozyme, and a hybrid form (MB). PGAM1 mutations lead to muscle phosphoglycerate mutase deficiency, a.k.a. glycogen storage disease X.

Amine Oxidase Copper Containing 3 , also referred to AOC3, a copper amine oxidase with a topaquinone cofactor.
AOC3 is a cell adhesion protein which participates in recirculation & extravasation of lymphocyte by mediating the binding of lymphocytes to peripheral lymph node vascular endothelial cells in an L-selectin independent fashion.
Amine Oxidase Copper Containing 3 acts in adipogenesis.
The protein catalyzes the oxidative deamination of small primary amines such as methylamine, benzylamine & aminoacetone in a reaction that produces an aldehyde, ammonia and H2O2.

Betaine-Homocysteine Methyltransferase 2 (BHMT2) is involved in the regulation of homocysteine metabolism. Homocysteine is a sulfur-containing amino acid which has a key role in methylation reactions. Transfer of the methyl group from betaine to homocysteine generates methionine, which donates the methyl group to methylate DNA, proteins, lipids, and other intracellular metabolites. BHMT2 is one of two methyl transferases which can catalyze the transfer of the methyl group from betaine to homocysteine. BHMT2 converts homocysteine to methionine using S-methylmethionine (SMM) as a methyl donor. Homocysteine metabolism anomalies are implicated in disorders varying from vascular disease to neural tube birth defects such as spina bifida.

Celiac disease is an enteropathy that is characterized by intestinal lesions of variable severity. Tissue-type transglutaminase (tTG) is believed to be the predominant autoantigen for celiac disease and the corresponding autoantibodies show higher sensitivity and specificity than anti-gliadin antibodies. Highly pure recombinant human tTG is now available to replace the traditionally used tTG fraction from guinea pig.
Tissue-type transglutaminase antigens have been specifically modified for improved handling: exchange of an active site amino acid eliminates the protein cross-linking activity of the enzyme, while maintaining the native three-dimensional structure and the enzyme's secondary GTPase activity. This engineering assures reproducible properties of the antigen preparations through the absence of variable and ill-defined covalent aggregates of tTG antigen and host cell proteins.

Antioxidant enzyme Glutathione S- Transferase (GST) is thought to do the primary cellular defense mechanism against reactive oxygen species. GST reduces lipid hydroperoxides through its Se-independent glutathione peroxidase activity. The enzyme also detoxifies lipid peroxidation end products such as 4-hydroxynonenal (4-HNE).
The soluble GST is a 26 kDa protein which occurs as a dimer in all aerobic organisms. Each monomer has two domains, one that binds GSH and is an /-structure similar to thioredoxin and the other, all helical, that binds the hydrophobic substrate. The GST -fusion protein expression system is a widely used recombinant protein expression system that allows a peptide or a regulatory protein domain to be expressed as a fusion to the C-terminus of Schistosoma japonicum GST. Fusion proteins also possess GST -enzymatic activity and can undergo dimerization similar to in vivo. The fusion protein can be purified via GST -affinity column chromatography. In most cases, the desired peptides or domains are removed from GST by applying a specific protease that recognizes and cleaves the linker between the protein domain and GST. The technique has been widely used to generate different kinds of proteins for crystallization, molecular immunology studies, the production of vaccines and studies involving protein-protein and protein-DNA interactions.

Streptokinase is an extracellular metallo-enzymeproduced by beta-haemolytic streptococcusand is used as an effective and cheap clot-dissolving medicationin some cases of myocardial infarction(heart attack) and pulmonary embolism.
It belongs to a group of medications known as fibrinolytics, and works by activating plasminogenthrough cleavage to produce plasmin.

DsbA appears to be necessary for correct formulation of disulfide bonds in exported proteins in vivo. DsbA is useful as a standard in immunoblotting. This protein catalyses the reduction and exchange of disulfide bonds and the oxidation of free sulfhydryl groups in vitro. It is the strongest oxidant of the thioredoxin superfamily. This thio/disulfide oxidoreductase is required for efficient disulfide bond formation in the periplasm of E. coli.

Aldolase C Fructose-Bisphosphate (ALDOC) belongs to the class I fructose-bisphosphate aldolase family. ALDOC is a glycolytic enzyme which catalyzes the reversible aldol cleavage of fructose-1,6-biphosphate and fructose 1-phosphate to dihydroxyacetone phosphate and either glyceraldehyde-3-phosphate or glyceraldehydes respectively. ALDOC is expressed exclusively in the hippocampus and Purkinje cells of the brain.

Carbonic anhydrases (CAs) are a large family of zinc metalloenzymes which catalyze the reversible hydration of carbon dioxide. These metalloenzymes participate in various biological processes, including respiration, calcification, acid-base balance, bone resorption, and the formation of aqueous humor, cerebrospinal fluid, saliva, and gastric acid. The metalloenzymes exhibit extensive diversity in tissue distribution and in their subcellular localization. Carbonic Anhydrase XI (CA11) is probably a secreted protein, nevertheless, drastic changes at active site residues completely conserved in CA isozymes with catalytic activity, make it unlikely that CA11 has carbonic anhydrase activity. CA11 shares properties in common with 2 other acatalytic CA isoforms, CA VIII and CA X. CA11 is amply expressed in the brain, and may have a general role in the central nervous system.

Glutamate-cysteine ligase (GCLM) is the first rate limiting enzyme of glutathione synthesis. The GCLM enzyme is comprised of 2 subunits, a heavy catalytic subunit and a light regulatory subunit. GCLM deficiency is associated with some forms of hemolytic anemia.

Human Phosphoserine phosphatase (hPSP) is an important enzyme in the phosphorylated pathway of serine biosynthesis, which contributes a major portion of the endogenous L-serine. Similar to known L-3-phosphoserine phosphatases, it catalyzed the Mg2+-dependent hydrolysis of L-phosphoserine and an exchange reaction between L-serine and L-phosphoserine. Recently, its complex structures reveal that the open-closed environmental change of the active site, generated -helical bundle domain, is important to substrate by local rearrangement of the recognition and hydrolysis.

Enteropeptidase or enterokinase is an enzyme involved in human digestion. It is produced by cells in the duodenum wall, and is secreted from duodenum's glands, the crypts of Lieberk?hn, whenever ingested food enters the duodenum from the stomach. Enteropeptidase has the critical job of turning trypsinogen (a zymogen) to trypsin, indirectly activating a number of pancreatic digestive enzymes. Enteropeptidase is a serine protease enzyme (EC 3.4.21.9). Enteropeptidase is a part of the Chymotrypsin-clan of serine proteases, and is structurally similar to these proteins.

Lysophospholipase-like protein 1 (LYPLAL1) is a member of the AB hydrolase 2 family. LYPLAL1 doesn’t exhibit phospholipase nor triacylglycerol lipase activity, able to hydrolyze only short chain substrates as a result of its shallow active site.

Inducible T-Cell Costimulator Ligand also known as ICOSLG, is part of the B7 family of co-stimulatory molecules related to B7-1 and B7-2. ICOSLG is a transmembrane glycoprotein with extracellular IgV and IgC domains, in addition it binds to ICOS on activated T cells. The dependent signaling of ICOSLG takes part in a proliferative response.

PCBD1 enzyme takes part in phenylalanine hydroxylation. PCBD1 deficiency results in hyperphenylalaninemia. PCBD1 enzyme controls the homodimerization of HNF1. PCBD1 takes part in tetrahydrobiopterin biosynthesis. PCBD1 prevents the formation of 7-pterins and accelerate the formation of quinonoid-BH2. PCBD1 is a coactivator for HNF1A-dependent transcription.