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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.

OTC is a member of the ATCase/OTCase family. OTC has a key part in the urea cycle, catalyzing the second step in this pathway: the transformation of L-orthinine and carbamoyl phosphate to L-citrulline. In humans, the urea cycle is a vital pathway to detoxification of ammonia. Alterations in the gene encoding OTC are linked to the X-linked disorder OTCD (ornithine carbamoyltransferase deficiency). OTCD disorder of the urea cycle is characterized by hyperammonemia.

BDH1 belongs to the short-chain dehydrogenase/reductase gene family. BDH1 forms a homotetrameric lipid-requiring enzyme of the mitochondrial membrane and has a specific necessity for phosphatidylcholine for optimal enzymatic activity. BDH1 catalyzes the interconversion of acetoacetate and (R)-3-hydroxybutyrate, the 2 main ketone bodies formed during fatty acid catabolism.

Paraoxonase-1 or PON1 is part of the paraoxonase group of proteins. PON1 is an enzyme, responsible to the toxic metabolites of a different of organophosphorus insecticides hydrolyzation. Furthermore, PON1 is a dominant anti-atherosclerotic part of HDL. The enzyme needs PPAR-gamma for activation, leading to synthesis and release of paraoxonase 1 from the liver tissue, resulting in atherosclerosis reduction. PON1 has many qualities for atheroprotective through inflammatory lipid peroxides metabolism. This enzyme can hydrolyze a large number of substrates, for example cyclic carbonates, lactones, nerve gases etc.

Adenylate kinases play a role in regulating the adenine nucleotide composition within a cell by catalyzing the reversible transfer of phosphate groups among adenine nucleotides. There are 3 types of adenylate kinase isozymes, AK1, AK2, and AK3 in vertebrates. Expression of these isozymes are tissue-specific and developmentally regulated. AK2 is localized in the mitochondrial intermembrane space and is involved in apoptosis. AK2 is mutated in individuals with reticular dysgenesis.

Translocase of Outer Mitochondrial Membrane 34 (TOMM34) which is found in the cytoplasm and sometimes associated with the outer mitochondrial membrane is involved in the import of precursor proteins into mitochondria. TOMM34 has a chaperone-like activity, binding the mature portion of unfolded proteins and aiding their import into mitochondria. TOMM34 has a weak ATPase activity and contains 6 TPR repeats.

IVD is a mitochondrial matrix enzyme that is part of the cyl-CoA dehydrogenase family which catalyzes the third step in leucine catabolism. The genetic deficiency of IVD leads to a buildup of isovaleric acid, which is toxic to the central nervous system and results in isovaleric acidemia. IVD is a homotetrameric flavoenzyme which catalyzes the conversion of isovaleryl-CoA to 3-methylcrotonyl-CoA.

ATPaseTransporting Beta 2 (ATP1B2) is the non-catalytic component of the active enzyme, which catalyzes the hydrolysis of ATP coupled with the exchange of Na+ and K+ ions across the plasma membrane. The precise function of the beta-2 subunit is not known. The ATP1B2 protein is composed of 3 subunits: alpha (catalytic), beta and gamma.

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.

MRPL28 is found in a variety of normal tissues such as spleen, testis, thymus, liver, kidney, brain, adrenal, lung and retinal tissue. 39S ribosomal protein L28, mitochondrial (MRPL28), is a part of the ribosomal protein L28P family. Mammalian mitochondrial ribosomal proteins encoded by nuclear genes and helps in protein synthesis within the mitochondrion. Mitochondrial ribosomes (mitoribosomes) consist of a small 28S subunit and a large 39S subunit. MRPL28 is an important therapeutic reagent for HLA-A24 (A24) patients since this antigen is distinguished by tumor-infiltrating lymphocyte (TIL) 1290, which targets the A24 serotype.

Glycine amidinotransferase mitochondrial (GATM) is a mitochondrial enzyme which is a member of the amidinotransferase family. The GATM enzyme is involved in creatine biosynthesis, where it catalyzes the transfer of a guanido group from L-arginine to glycine, resulting in guanidinoacetic acid, the immediate precursor of creatine, which has an imperative role in energy metabolism in muscle tissues. GATM is significant in embryonic and central nervous system development. GATM gene mutations cause arginine:glycine amidinotransferase deficiency, an inborn error of creatine synthesis characterized by mental retardation, language impairment, and behavioral disorders.

NADH Dehydrogenase Flavoprotein 2 (NDUFV2) is a 24 kDa Core subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (Complex I) which is a part of the minimal assembly required for catalysisthe. NDUFV2 is aslo involved in electron transfer. Mutations in NDUFV2 are implicated in Parkinson's disease, bipolar disorder, schizophrenia, and have been discovered in one case of early onset hypertrophic cardiomyopathy and encephalopathy.

Protein tyrosine phosphatase mitochondrial 1 (PTPMT1) is a broadly expressed PTP membrane protein with high expression levels in pancreatic beta cells. The PTPMT1 protein is completely restricted to the matrix face of the inner membrane of the mitochondrion. PTPMT1 is responsible for dephosphorylating mitochondrial proteins and thus has a major role in the production of ATP. PTPMT1 exhibits a specific preference for the lipid signaling molecule phosphatidylinositol 5-phosphate as substrate.

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.

MAT1A catalyzes a two-step reaction that involves the transfer of the adenosyl moiety of ATP to methionine to form S-adenosylmethionine and tripolyphosphate, which is subsequently cleaved to PPi and Pi. S-adenosylmethionine is the source of methyl groups for most biological methylations. MAT1A is found as a homotetramer (MAT I) or a homodimer (MAT III) whereas a third form, MAT II (gamma), is encoded by the MAT2A gene. Mutations in MAT1A gene are associated with methionine adenosyltransferase deficiency. MAT1A expression also correlates with a differentiated phenotype, whereas liver cells expressing MAT2A present a dedifferentiated phenotype and lowered AdoMet synthesis. Likewise, NFκB and TNFα cause a switch from MAT1A to MAT2A expression in human hepatocellular carcinoma (HCC), which facilitates cancer cell growth.

Acyl CoA dehydrogenase is the enzymeused to catalyzethe first step of ?-oxidationin Fatty acid metabolism.
Acyl-coenzyme A (CoA) dehydrogenases (ACADs) are a family of mitochondrial enzymes that catalyze the first dehydrogenation step in the bets-oxidation of fatty acyl-CoA derivatives. Several human ACADs exist and all ACADs catalyze the same initial dehydrogenation of the substrate at the beta-carbon atom and require electron transfer flavoprotein as an alectron acceptor. The predicted 415-amino acid ACAD8 protein contains many of the residues conserved in most other ACADs, including an active site glutamic acid residue and residues important for tetramer formation.

Mammalian mitochondrial ribosomal proteins are encoded by nuclear genes and aid in protein synthesis within the mitochondrion. Mitochondrial ribosomes (mitoribosomes) comprised of a small 28S subunit and a large 39S subunit. Among different species, the proteins comprising the mitoribosome vary greatly in sequence, and sometimes in biochemical properties, thus preventing simple recognition by sequence homology. Mitochondrial Ribosomal Protein L2 (MRPL2) is a 39S subunit protein which is a member of the EcoL2 ribosomal protein family.

ATPase inhibitory factor 1 (ATPIF1) attaches to the C-terminal region of a beta subunit of the F1-ATPase at low pH values and, through interference of the beta and gamma subunit interaction, ATPIF1 controls the activity of the F1 (the hydrophilic catalytic core), F0 (the membrane embedded protein channel) ATPase. ATPIF1 overexpression in a number of human carcinomas additionally reinforces its participation in oncogenesis and offers insight into the transformed metabolism of cancer cells, including the reprogramming of energy metabolism in relation to glycolysis. Endogenous F1F(o)-ATPase inhibitor curbing ATP depletion when the mitochondrial membrane potential drops below a threshold and the F1F(o)-ATP synthase begins hydrolyzing ATP to pump protons out of the mitochondrial matrix.

Deoxyuridine Triphosphatase (DUT) is a ubiquitous enzyme that functions in nucleotide metabolism. Deoxyuridine Triphosphatase, in the presence of magnesium ions, is responsible for hydrolyzing dUTP to dUMP and diphosphate. This reaction is imperative for keeping the intracellular dUTP concentration low so that uracil does not become incorporated into DNA. Extensive integration of uracil into DNA can eventually lead to cell death. This suggests that DUT is crucial for cell viability, further implying that it is a prospective target for anticancer therapy.

ACADL is a homotetramer belonging to the acyl-CoA dehydrogenase family. ACADL takes part in the catabolism of fatty acids and amino acids and is a key source of energy for the heart and skeletal muscle. Mutation in the ACADL gene results in non-ketotic hypoglycemia and hypotonia (muscle weakness).

ATPaseTransporting Beta 2 (ATP1B2) is the non-catalytic component of the active enzyme, which catalyzes the hydrolysis of ATP coupled with the exchange of Na+ and K+ ions across the plasma membrane. The precise function of the beta-2 subunit is not known. The ATP1B2 protein is composed of 3 subunits: alpha (catalytic), beta and gamma.

Fucosyltransferase 7 (FUT7) is a golgi stack membrane protein which is involved in the creation of sialyl-Lewis X antigens. The FUT7 protein leads the synthesis of the E-selectin-binding sialyl-Lewis X moiety. FUT7 catalyzes alpha-1,3 glycosidic linkages involved in the expression of sialyl Lewis X antigens.

AK1 is a small ubiquitous enzyme which is essential for maintenance and cell growth. It is involved in the regulation of adenine nucleotide composition within a cell by catalyzing the reversible transfer of the terminal phosphate group between ATP and AMP. The AK1 protein is found in the cytosol of skeletal muscle, brain and erythrocytes. Defects in the AK1 gene are the cause of a form of hemolytic anemia.

ALDH2 is part of the aldehyde dehydrogenase family of proteins which catalyze the chemical transformation from acetaldehyde to acetic acid. ALDH2 is the second enzyme of the major oxidative pathway of alcohol metabolism. ALDH2 has 2 major liver isoforms: cytosolic and mitochondrial, which differ by their electrophoretic mobilities, kinetic properties, and subcellular localizations. Nearly all Caucasians have 2 major isozymes, whereas roughly 50% of Orientals have only the cytosolic isozyme, omitting the mitochondrial isozyme. The extremely higher rate of acute alcohol intoxication with Orientals compared to Caucasians is due to the fact of the absence of mitochondrial isozyme. ALDH2 has a low Km for acetaldehydes, and is localized in mitochondrial matrix.