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Renin is a highly specific endopeptidase which generates angiotensin I from angiotensinogen in the plasma. angiotensin I is an important regulator of blood pressure and electrolyte balance. Renin initiates a cascade of reactions that produce an elevation of blood pressure and increased sodium retention by the kidney.

GAPDH is a catalytic enzyme normally known to play a role in glycolysis. GAPDH exists as a tetramer composed of 36-kDa subunits and has a range of intracellular functions. GAPDH catalyzes the reversible reduction of 1,3-bisphosphoglycerate to glyceraldehyde 3-phosphophate in the presence of NADPH. Besides functioning as a glycolytic enzyme in cytoplasm, GAPDH has function in intracellular processes such as membrane fusion, microtubule bundling, phosphotransferase activity, nuclear RNA export, DNA replication and DNA repair. GAPDH catalyzes a vital energy-yielding step in carbohydrate metabolism, the reversible oxidative phosphorylation of glyceraldehyde-3-phosphate in the presence of inorganic phosphate and nicotinamide adenine dinucleotide (NAD). The enzyme exists as a tetramer of identical chains.

Glycerol-3-phosphate dehydrogenase 1-like protein (GPD1L) converts sn-glycerol 3-phosphate to glycerone phosphate. GPD1L is found in the cytoplasm, associated with the plasma membrane, where it binds the sodium channel, voltage-gated, type V, alpha subunit (SCN5A). Mutations in the GPD1L gene are the cause of SIDS (sudden infant death syndrome) and Brugada syndrome type 2 (an autosomal dominant tachyarrhythmia).

The protein encoded by this gene is a cytokine that regulates T and natural killer cell activation and proliferation. This cytokine and interleukine 2 share many biological activities. They are found to bind common hematopoietin receptor subunits, and may compete for the same receptor, and thus negatively regulate each other's activity. The number of CD8+ memory cells is shown to be controlled by a balance between this cytokine and IL2. This cytokine induces the activation of JAK kinases, as well as the phosphorylation and activation of transcription activators STAT3, STAT5, and STAT6. Studies of the mouse counterpart suggested that this cytokine may increase the expression of apoptosis inhibitor BCL2L1/BCL-x(L), possibly through the transcription activation activity of STAT6, and thus prevent apoptosis. Two alternatively spliced transcript variants of this gene encoding the same protein have been reported.

NQO2 is a flavoprotein that catalyzes the 2-electron reduction of diverse quinones, redox dyes, and the vitamin K menadione. NQO2 mainly uses dihydronicotinamide riboside (NRH) as the electron donor. NQO2 catalyzes the metabolic detoxification of quinones and their derivatives to hydroquinones. This detoxification process protects cells against quinone-induced oxidative stress, cytotoxicity and mutagenicity.

X-Prolyl Aminopeptidase-1, also known as XPNPEP1 is a member of the peptidase M24B family. XPNPEP1 encodes the cytosolic form of a metalloaminopeptidase which catalyzes the cleavage of the N-terminal amino acid adjacent to a proline residue. Furthermore, XPNPEP1 plays a role in degradation as well as maturation of tachykinins, neuropeptides and peptide hormones.

Hepatitis B is one of a few known non-retroviralviruses which employ reverse transcriptionas a part of its replication process. (HIV, a completely unrelated virus, also uses reverse transcription, but it is a retrovirus.) HBV invades the cell by binding to surface receptor and become internalized. The viral core particles then migrate to the hepatocyte nucleus and the partially double-stranded, relaxed circular genomes (RC-DNA) are repaired to form a covalently closed circular DNA (cccDNA), which is the template for viral genomic and sub-genomic RNAs by cellular RNA polymerase II. Of these, the pregenomic RNA (pgRNA is selectively packaged into progeny capsids and is then reverse-transcribed into new RC-DNA. The core can either bud into the endoplasmic reticulum to be enveloped or exported from the cell or recycled back into the genome for conversion to cccDNA.

NUDT1 is an enzyme that hydrolyzes oxidized purine nucleoside triphosphates, such as 8-oxo-dGTP, 8-oxo-dATP, 2-hydroxy-dATP, and 2-hydroxy rATP, to monophosphates, thereby preventing misincorporation of 8-oxo-dGTP into DNA thus preventing A:T to C:G transversions. NUDT1 is found mostly in the cytoplasm, with some in the mitochondria, suggesting that it is involved in the sanitization of nucleotide pools both for nuclear and mitochondrial genomes. Moreover, NUDT1 is expressed at much higher levels in proliferating cells than in resting cells. Misincorporation of oxidized nucleoside triphosphates into DNA/RNA during replication and transcription can cause mutations which may result in carcinogenesis or neurodegeneration.

Cathepsin-L also known as CTSL is a member of the peptidase C1 family. CTSL, is a dimer composed of disulfide-linked heavy and light chains, both formed from a single protein precursor. Furthermore, CTSL is a lysosomal cysteine proteinase which takes a main part in intracellular protein catabolism. CTSL substrates include collagen and elastin, as well as alpha-1 protease inhibitor, which is the most important controlling element of neutrophil elastase activity. CTSL has been implicated in a number of pathologic processes, including myofibril necrosis in myopathies and in myocardial ischemia, and in the renal tubular response to proteinuria. Multiple alternatively spliced transcript variants have been found for CTSL.

Dihydrofolate reductase (DHFR) is an enzyme that reduces dihydrofolic acid to tetrahydrofolic acid, with NADPH as electron donor that can be converted to the kinds of tetrahydrofolate cofactors applied in 1-carbon transfer chemistry. DHFR converts dihydrofolate into tetrahydrofolate, which is a methyl group shuttle required for the de novo synthesis of purines, thymidylic acid, and specific amino acids. Even though the functional DHFR gene is mapped to chromosome 5, numerous intronless processed pseudogenes or dihydrofolate reductase-like genes are identified on separate chromosomes.
DHFR deficiency is associated with megaloblastic anemia.DHFR knockdown plays a role in the anticancer activity of 2-hydroxyoleic acid.
DHFR gene insertion/deletion polymorphism is linked to variation in serum and red blood cell folate concentrations in women.

Arylsulfatase A (ARSA) hydrolyzes cerebrosidesulfate to cerebroside and sulfate. ARSA is inhibited by phosphate. The phosphate develops a covalent bond with the active site 3-oxoalanine. ARSA gene defects cause metachromatic leucodystrophy (MLD), a progressive demyelination disease which results in various neurological symptoms and ultimately death.

IL17 is a proinflammatory cytokine produced by activated T cells. IL-17 regulates the activities of NF-kappaB and mitogen-activated protein kinases. Interleukin-17 can stimulate the expression of IL6 and cyclooxygenase-2 (PTGS2/COX-2), as well as enhance the production of nitric oxide (NO). High levels of IL-17 are associated with several chronic inflammatory diseases including rheumatoid arthritis, psoriasis and multiple sclerosis.

IL4 is a pleiotropic cytokine produced by activated T cells. IL4 is a ligand for interleukin 4 receptor. The interleukin 4 receptor also binds to IL13, which may contribute to many overlapping functions of this cytokine and IL13. STAT6, a signal transducer and activator of transcription, has been shown to play a central role in mediating the immune regulatory signal of this cytokine. This gene, IL3, IL5, IL13, and CSF2 form a cytokine gene cluster on chromosome 5q, with this gene particularly close to IL13. IL4, IL13 and IL5 are found to be regulated coordinately by several long-range regulatory elements in an over 120 kilobase range on the chromosome. Two alternatively spliced transcript variants of this gene encoding distinct isoforms have been reported.

NRAS binds GDP/GTP and has intrinsic GTPase activity. NRAS is a membrane protein that shuttles between the Golgi apparatus and the plasma membrane. This transport is regulated through palmitoylation and depalmitoylation by the ZDHHC9-GOLGA7 complex. NRAS is activated to a GTP-bound form by a GTPase activating protein and inactivated to a GDP-bound form by a guanine nucleotide-exchange factor. Defects in this NRAS gene result in juvenile myelomonocytic leukemia.

BRCC3 is a subunit of the BRCA1-BRCA2-containing complex (BRCC), which is an E3 ubiquitin ligase. BRCC3 is also thought to be involved in the cellular response to ionizing radiation and progression through the G2/M checkpoint.

PRDX3 is part of the peroxiredoxin family of antioxidant enzymes, that reduces hydrogen peroxide and alkyl hydroperoxides. PRDX3 is particularly located in the mitochondria and involved in the regulation of cellular redox status by serving as a primary line of defense against H2O2 produced during respiration. PRDX3 is a significant regulator of the abundance of mitochondrial H(2)O(2), which itself promotes apoptosis in cooperation with other mediators of apoptotic signaling. PRDX3 mitochondrial protein is significantly decreased in Alzheimer Disease and Down Syndrome.

Cathepsins B, C, H, L, S, V, X/Z/P and 1 are cysteine proteases of the papain family. Cathepsin C is also known as DPPI (dipeptidyl-peptidase I). Cathepsin A is a serine carboxypeptidase and Cathepsin D and E are aspartic proteases. As lysosomal proteases, cathepsins play an important role in protein degradation. Because of their redistribution or increased levels in human and animal tumors, cathepsins may have a role in invasion and metastasis. Cathepsins are synthesized as inactive proenzymes and processed to become mature and active enzymes. Endogenous protein inhibitors, such as cystatins and some serpins, inhibit active enzymes.

S100A1 is a member of the S100 family of calcium binding proteins with EF-hand type Ca+2 binding motive. S100A1 (Calcium Binding Protein A1) is involved in the activation of sarcoplasmatic calcium release and the regulation of intermediate filament polymerization. S100A1 may function in stimulation of Ca2+-induced Ca2+ release, inhibition of microtubule assembly, and inhibition of protein kinase C-mediated phosphorylation. Reduced expression of S100A1 has been implicated in cardiomyopathies.
S100 proteins are localized either in the cytoplasm or the nucleus of a wide range of cells. There are at least 13 members in the S100 gene family, which are located as a cluster on chromosome 1q21.

AXIN1 is a cytoplasmic protein, which contains a regulation of G-protein signaling (RGS) domain and a dishevelled and axin (DIX) domain. Axin1 is has been characterized as a tumor suppressor. In addition, Axin1 has an essential role in the formation of the embryonic neural axis. It has also been reported that Axin is found in mitotic spindles and centrosomes. AXIN1 interacts with adenomatosis polyposis coli, catenin beta-1, glycogen synthase kinase 3 beta, protein phosphate 2, and itself. AXIN1 functions as a negative regulator of the WNT1 signaling pathway and is able to induce apoptosis. Axin can be identified in a mouse mutant strain, created by random integration of a transgene. Mutations in the AXIN1 gene are linked to hepatocellular carcinoma, hepatoblastomas, ovarian endometriod adenocarcinomas, and medullablastomas.

Il-6 is a cytokine with a wide variety of biological functions: it plays an essential role in the final differentiation of b-cells into ig-secreting cells, it induces myeloma and plasmacytoma growth, it induces nerve cells differentiation, in hepatocytes it induces acute phase reactants.

A fusion tag called FLAG consists of eight amino acids (AspTyrLysAspAspAspAspLys) including an enterokinase-cleavage site. FLAG is specifically designed for immunoaffinity chromatography. It allows elution under non-denaturing conditions. Several antibodies against this peptide have been developed. One antibody denoted as M1 binds the peptide in the presence of bivalent metal cations preferably Ca(+). Elution is effected by chelating agents. Another strategy is competitive elution with excess of free Flag Peptide.
The FLAG peptide purifies and detects recombinant fusion proteins. FLAG peptide is useful in Western blotting, immunocytochemistry, immunoprecipitation, flow cytometry, protein purification, and in the study of protein-protein interactions, cell ultrastructure, and protein localization. Flag peptide is a hydrophilic tag which significantly improves the detection and purification of recombinant fusion proteins.

Epoxide hydrolase is a vital biotransformation enzyme which converts epoxides from the degradation of aromatic compounds to trans-dihydrodiols that can be conjugated and excreted from the body. Epoxide hydrolase functions in both the activation and detoxification of epoxides. Mutations in the EPHX1 gene cause preeclampsia, epoxide hydrolase deficiency or increased epoxide hydrolase activity.

ACADS is a tetrameric mitochondrial flavoprotein, which is part of the acyl-CoA dehydrogenase family. ACADS catalyzes the first step of the mitochondrial fatty acid beta-oxidation pathway. Mutations in ACADS have been associated with Short Chain Acyl-CoA Dehydrogenase Deficiency.

SORD enzyme is part of of the zinc-containing alcohol dehydrogenase family that is broadly expressed in kidney and in the lens eye. SORD enzymatically catalyzes the zinc-dependent interconversion of polyols, such as sorbitol and xylitol, to their respective ketoses.