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Prostaglandin-H2 D-isomerase (PTGDS) is a glutathione-independent prostaglandin D synthase which catalyzes the conversion of prostaglandin H2 (PGH2) to postaglandin D2 (PGD2). PTGDS is may have vital roles in both maturation and maintenance of the central nervous system and male reproductive system. PTGDS is the most abundant protein in the cerebral spinal fluid and recent evidence suggests that PTGDS acts as a beta-amyloid chaperone and may play a role in the deposition of Ab plaques in Alzheimer’s disease.

UPRT is a uracil phosphoribosyltransferase, that catalyzes the alteration of uracil and 5-phosphoribosyl-1-R-diphosphate to uridine monophosphate (UMP). This reaction is a significant part of nucleotide metabolism, specifically the pyrimidine salvage pathway. UPRT is restricted to the nucleus and cytoplasm and is a possible target for rational design of drugs to cure cancer and parasitic infections.

NDUFS2 is a core subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (Complex I) which is a part of the minimal assembly required for catalysis. Complex I takes part in the transfer of electrons from NADH to the respiratory chain. Histidine NADH Dehydrogenase Fe-S Protein 2 (NDUFS2) is required for catalytic activity. Imperfections in NDUFS2 are the source of complex I mitochondrial respiratory chain deficiency, which is characterized by many symptoms including liver failure, cardiomyopathy and neurodegeneration.

Mitochondrial Ribosome Recycling Factor (MRRF) is a member of the RRF family. MRRF attaches to the large ribosomal subunit in the cleft which has a peptidyl transferase center. MRRF controls the release of ribosome from messenger RNA at the termination of protein biosynthesis. Also, it may intensify the efficacy of translation by recycling ribosome from one round of translation to another.

PRPS1 catalyzes the synthesis of phosphoribosylpyrophosphate (PRPP) that is essential for nucleotide synthesis. PRPS1 catalyzes the phosphoribosylation of ribose 5-phosphate to 5-phosphoribosyl-1-pyrophosphate, which is essential for purine metabolism and nucleotide biosynthesis. Defects in PRPS1 result in phosphoribosylpyrophosphate synthetase superactivity, Charcot-Marie-Tooth disease X-linked recessive type 5 and Arts Syndrome.

ALDH6A1 or Methylmalonate-semialdehyde dehydrogenase [acylating], mitochondrial is a mitochondrial methylmalonate semialdehyde dehydrogenase. ALDH6A1 participates in the valine and pyrimidine catabolic pathways. ALDH6A1 catalyzes the irreversible oxidative decarboxylation of malonate, propionyl-CoA and methylmalonate semialdehydes to acetyl. ALDH6A1 deficiency is distinguished by high levels of beta-alanine, 3-hydroxypropionic acid, and the two isomers of 3-amino and 3-hydroxyisobutyric acids in urine organic acids.

AASDHPPT is a member of the P-Pant transferase superfamily. AASDHPPT catalyzes the post-translational modification of target proteins by phosphopantetheine and can transfer the 4'-phosphopantetheine moiety from coenzyme A to a serine residue of a broad range of acceptors, such as the acyl carrier domain of FASN (in vitro). AASDHPPT is similar to Saccharomyces cerevisiae LYS5, which is required for the activation of the alpha-aminoadipate dehydrogenase in the biosynthetic pathway of lysine. AASDHPPT is found in the heart, skeletal muscle, placenta, testis, brain, pancreas, liver and kidney. It’s been suggested that defects in the human AASDHPPT gene result in pipecolic acidemia.

2-Enoyl-Coenzyme A (CoA) Hydratase, Beta (HADHB) is the beta subunit of the mitochondrial trifunctional protein, that catalyzes the last 3 phases of mitochondrial beta-oxidation of long chain fatty acids. HADHB binds RNA and reduces the stability of various mRNAs. Mutations in HADHB cause trifunctional protein deficiency.

Ornithine aminotransferase is a key enzyme in the pathway that converts arginine and ornithine into the major excitatory and inhibitory neurotransmitters glutamate and GABA. Ornithine aminotransferase (OAT) is a 49kDa nucleus-encoded protein imported into mitochondria to give the mature 48kDa OAT polypeptide. It is found in humans, animals, insects, plants and microorganisms. The OAT has a sex-differential expression in the mouse kidney. OAT plays central physiological roles in amino acid metabolism. OAT shows a large structural and mechanistic similarity to other enzymes from the subgroup III of aminotransferases that transfer an amino group from a carbon atom which doesn’t carry a carboxyl function. OAT is vital for nitrogen recycling from arginine but not for the stress-induced proline accumulation. OAT enzyme deficiency causes the autosomal recessive eye disease Gyrate Atrophy.

Phosphoribosyl Pyrophosphate Synthetase 2, also known as PRPS2 is a member of the ribose-phosphate pyrophosphokinase family. PRPS2 catalyzes the synthesis of 5-phosphoribosyl 1-pyrophosphate from ATP and D-ribose 5-phosphate.

Phosphoserine aminotransferase (PSAT1) catalyzes the conversion of 3-phosphohydroxypyruvate into 3-phosphoserine which is dephosphorylated consequently by phosphoserine phosphatase to form L-serine. PSAT1 is probably a phosphoserine aminotransferase, based on similarity to proteins in mouse, rabbit, and Drosophila. PSAT1 is expressed at high levels in the brain, liver, kidney and pancreas, and very weakly expressed in the thymus, prostate, testis and colon. Defects in the PSAT1 gene are the cause of phosphoserine aminotransferase deficiency (PSATD). PSATD is distinguished biochemically by low plasma and cerebrospinal fluid concentrations of serine and glycine and clinically by intractable seizures, acquired microcephaly, hypertonia, and psychomotor retardation.

ATPase Transporting Beta 1 (ATP1B1) is a part of the family of Na+/K+ and H+/K+ ATPases beta chain proteins, and the subfamily of Na+/K+ -ATPases. Na+/K+ -ATPase is an essential membrane protein accountable for establishing and maintaining the electrochemical gradients of Na and K ions over the plasma membrane. These gradients are vital for osmoregulation, for sodium-coupled transport of a range of organic and inorganic molecules, and for electrical excitability of muscle and nerve. ATP1B1is combined of 2 subunits, a large catalytic subunit (alpha) and a smaller glycoprotein subunit (beta). The beta subunit regulates the number of sodium pumps transported to the plasma membrane through assembly of alpha/beta heterodimers. ATP1B1 is a beta 1 subunit.

PTGES3 takes part as a cochaperone and is involved in signal transduction.
PTGES3 is a molecular chaperone that localizes to genomic response elements in a hormone-dependent manner and disrupts receptor-mediated transcriptional activation, by promoting disassembly of transcriptional regulatory complexess. PTGES3 is necessary for appropriate functioning of the glucocorticoid and other steroid receptors.
PTGES3 localizes to genomic response elements in a hormone-dependent method and disrupts receptor-mediated transcriptional activation, by promoting disassembly of transcriptional regulatory complexes.

Mammalian mitochondrial ribosomal proteins are encoded by nuclear genes and assist in protein synthesis within the mitochondrion. Mitochondrial ribosomes (mitoribosomes) consist of a small 28S subunit and a large 39S subunit (MRPL13 is a 39S subunit protein) and have an estimated 75% protein to rRNA composition compared to prokaryotic ribosomes, where this ratio is reversed. An additional difference between mammalian mitoribosomes and prokaryotic ribosomes is that the second contain a 5S rRNA. Among various species, the proteins comprising the mitoribosome differ greatly in sequence, and sometimes in biochemical properties, which prevents easy recognition by sequence homology.

ASS1 is involved in the urea cycle, which is a sequence of chemical reactions that is localized in liver cells. The urea cycle processes excess nitrogen that is generated as the body uses proteins. The surplus nitrogen is used to create a molecule called urea, which is excreted from the body in urine.

SEPSECS catalyzes the last step of sec synthesis by way of converting O-phosphoseryl-tRNA(sec) to selenocysteinyl-tRNA(sec) using selenophosphate as the selenium donor. Furthermore, SEPSECS protein is considered a specific marker of autoimmune hepatitis.

Mitochondrial antiviral signaling protein (MAVS) is vital for innate immune defense against viruses. MAVS is an intermediary protein essential in the virus-triggered IFN-beta signaling pathways. MAVS is involved in activation of transcription factors that regulate expression of IFN-beta and contributes to antiviral immunity.

NUDT9 is a member of a superfamily of Nudix hydrolases. NUDT9 functions as a highly specific adenosine diphosphate ribose pyrophosphatase which hydrolyzes ADP ribose to AMP and ribose 5'-phosphate. In addition, NUDT9 may be involved in the regulation of the menstrual cycle and may be related to the proliferation of glandular cells in the human endometrium.

Farnesyl-Diphosphate Farnesyltransferase 1, also known as FDFT1 is a membrane-associated enzyme sited at a branch point in the mevalonate pathway. FDFT1belongs to the phytoene/squalene synthase family. FDFT1 is the 1st specific enzyme in cholesterol biosynthesis, which catalyzes the dimerization of 2 molecules of farnesyl diphosphate in a two-step reaction to form squalene.

SRM is an enzyme which catalyzes the transfer of the propylamine group from S-adenosylmethioninamine to putrescine in the biosynthesis of spermidine. The polyamines putrescine, spermine and spermidine are ubiquitous polycationic mediators of cell growth and differentiation. The SRM protein is one of four enzymes in the polyamine-biosynthetic pathway and completes the final step of spermidine biosynthesis.

MAT2A is an important enzyme in cellular metabolism and catalyzes the formation of S-adenosylmethionine (SAMe) from L-methionine and ATP. MAT2A is expressed in extrahepatic tissues. In liver, MAT2A expression associates with growth, dedifferentiation, and cancer. NF-kappa B and AP-1 are necessary for basal MAT2A expression in HepG2 cells and mediate the increase in MAT2A expression in response to TNF-alpha. Up-regulation of MAT2A provides growth improvement and s-adenosylmethionine and methylthioadenosine thus can block mitogenic signaling in colon cancer cells. Lower expression of both MAT2A and MAT2beta and interfere with leptin signaling in liver cancer cells.

Nicotinamide Nucleotide Adenylyltransferase 2, also known as NMNAT2 is a member of the nicotinamide mononucleotide adenylyltransferase (NMNAT) enzyme family, members of which catalyze a vital step in NAD (NADP) biosynthetic pathway. Unlike the other human family member, which is localized to the nucleus, and is ubiquitously expressed; NMNAT2 is cytoplasmic, and is predominantly expressed in the brain. Two transcript variants encoding different isoforms have been found for NMNAT2. Among the diseases associated with NMNAT2 are tauopathy, and systemic lupus erythematosus.

GPD2 (Mitochondrial glycerol-3-phosphate dehydrogenase) is a Ca2+-sensitive, FAD-binding protein, which is located on the outer surface of the inner mitochondrial membrane. Two isoforms have been identified for mGPD: Isoform 1 is comprised of 727 a.a. residues, while isoform 2 lacks 126 a.a. residues of the N-terminus. GPD2 catalyses the oxidation of glycerol-3-phosphate to DHAP (dihydroxyacetone phosphate) with associated reduction of the enzyme-bound FAD. GPD2 is a testis-specific promoter of mitochondrial GPDH. GPD2 along with a cytosolic NAD-linked GPD forms the glycerol phosphate shuttle that uses the interconversion of G-3-P and DHAP to transfer reducing equivalents into mitochondria, which results in the reoxidation of NADH produced during glycolysis.
GPD2 deficiency contributes to the impairment of glucose-stimulated INS discharge in a number of animal models of non-INS dependent diabetes mellitus. GPD2 up-regulation as a result of a highly glycolytic environment contributes to the general increase in ROS generation and may lead to the progression of prostate cancer.

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.