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Ketohexokinase catalyzes the phosphorylation of fructose to produce fructose-1-phosphate, resulting in the utilization of ATP and creation of AMP. Ketohexokinase commences initial step in the metabolism of dietary fructose and is a significant regulator of hepatic glucose metabolism. Ketohexokinase is found in liver, renal cortex, and small intestine. Its deficiency causes the benign hereditary metabolic disorder essential fructosuria, leading to fructose being excreted in the urine. Ketohexokinase-dependent metabolism of fructose induces proinflammatory mediators in proximal tubular cells. ketohexokinase plays an unknown physiologic function that remains intact in essential fructosuria. Ketohexokinase expression is reduceed in human clear cell type of renal cell carcinoma.

Membrane Metalloendopeptidase, also known as MME is a zinc metallopeptidase which is expressed at the cell surface of various cells. MME degrades the amyloid beta peptide whose abnormal misfolding as well as aggregation in neural tissue has been implicated as the cause for Alzheimer's disease. MME is expressed in an extended range of tissues and is especially plentiful in the kidney. MME is also a common acute lymphocytic leukemia antigen which is a significant cell surface marker in the diagnosis of human acute lymphocytic leukemia (ALL). MME is used in hematological diagnosis because it is expressed by early B, pro-B and pre-B lymphocytes, and also by lymph node germinal centers.

Inositol monophosphatase1 (IMPA1) is responsible for the provision of inositol essential for synthesis of phosphatidylinositol and polyphosphoinositides. IMPA1 has a central role in the phosphatidylinositol signaling pathway by catalyzing the hydrolysis of inositol monophosphates. IMPA1 has been recognized as the pharmacological target for lithium action in the brain. The IMPA1 enzyme has a magnesium-dependent phosphatase activity and is inhibited by therapeutic concentrations of lithium. Inhibition of inositol monophosphate hydroylosis and ensuing depletion of inositol for phosphatidylinositol synthesis may perhaps explain the anti-manic and anti-depressive effects of lithium administered to treat bipolar disorder.

The 26S proteasome is a multicatalytic proteinase complex with a well ordered structure composed of two complexes- a 20S core and a 19S regulator. PSMD11 is a non-ATPase subunit of the 19S regulator. The 20S core is composed of four rings of 28 non-identical subunits; two rings are composed of 7 alpha subunits and two rings are composed of 7 beta subunits. The 19S regulator is composed of a base that contains six ATPase subunits and two non-ATPase subunits, and a lid that contains up to ten non-ATPase subunits. Proteasomes are spread throughout eukaryotic cells at a high concentration and cleave peptides in an ATP/ubiquitin-dependent process in a non-lysosomal pathway. An indispensable function of a modified proteasome, the immunoproteasome, is the processing of class I MHC peptides.

Glutaminyl-Peptide Cyclotransferase, also known as QPCT is a member of the glutaminyl-peptide cyclotransferase family. QPCT is responsible for the biosynthesis of pyroglutamyl peptides. Furthermore, QPCT is partial against acidic and tryptophan residues adjacent to the N-terminal glutaminyl residue and a lack of importance of chain length following the second residue. QPCT catalyzes N-terminal pyroglutamate formation, also in vitro, it catalyzes pyroglutamate formation of N-terminally truncated form of APP amyloid-beta peptides [Glu-3]-beta-amyloid.

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.

Caspase 3 Apoptosis-Related Cysteine Peptidase (CASP3) belongs to the cysteine-aspartic acid protease (caspase) family. Sequential activation of caspases plays a key role in the execution-phase of cell apoptosis. Caspases exist as inactive proenzymes which undergo proteolytic processing at conserved aspartic residues to generate 2 subunits, large and small, that dimerize to create the active enzyme. CASP3 protein cleaves and activates caspases 6, 7 and 9, and the protein itself is processed by caspases 8, 9 and 10. CASP3 is the leading caspase involved in the cleavage of amyloid-beta 4A precursor protein, which is linked with neuronal death in Alzheimer's disease. In addition, CASP3 is involved in the cleavage of huntingtin. CASP3 also cleaves and activates sterol regulatory element binding proteins (SREBPs) between the basic helix-loop-helix leucine zipper domain and the membrane attachment domain. CASP3 initiates cell adhesion in sympathetic neurons through RET cleavage.

MGMT is an enzyme that repairs O-6-methylguanine, a mutagenic DNA base damaged by endogenous and environmental alkylating agents and takes part in the cellular defense against the biological effects of O-6-methylguanine in DNA. MGMT repairs alkylated guanine in DNA by stoichiometrically transferring the alkyl group at the O-6 position to a cysteine residue in the enzyme. abnormal MGMT expression correlates with the prognosis in human solid cancers. MGMT decrease of expression is correlated with methylation. The human MGMT is a negative regulator of estrogen receptor-mediated transcription upon alkylation DNA damage. MGMT promoter hypermethylation plays an important role in the early steps of colorectal carcinogenesis. Abnormal promoter hypermethylation of MGMT gene is associated with oral squamous cell carcinomas.

melA is a member of the glycosyl hydrolase 4 family. melA catalyze the hydrolysis of saccharides containing o-1,6,-galactoside bonds. melA catalyze the same reaction in E.coli, human and yeast but is found in different cellular sections: The E.coli melA is a cytoplasmic protein and the human and yeast melA are secretory proteins. Thus, even though the active enzyme from all three species has almost an equal molecular weight, structural resemblances, as well as dissimilarities, are probable.

ALAD form porphobilinogen (a precursor of heme, cytochromes and other hemoproteins) by catalyzing the compression of 2 molecules of delta-aminolevulinate. ALAD catalyzes the second step in the porphyrin and heme biosynthetic pathway; zinc is vital for enzymatic activity. ALAD has 8 identical subunits and its enzymatic activity is inhibited by lead. Mutations in the ALAD structural gene are the source for high sensitivity to lead poisoning and acute hepatic porphyria.

ALDH5A1 is a mitochondrial NAD(+)-dependent succinic semialdehyde dehydrogenase, which is a member of the aldehyde dehydrogenase family of proteins. The ALDH5A1 protein functions as a mediator to the NADP+-dependent oxidation of aldehydes into acids and has an imperative role in the detoxification of alcohol-derived acetaldehyde, as well as in lipid peroxidation and in the metabolism of corticosteroids, biogenic amines and neurotransmitters. ALDH5A1 is expressed in various tissues, including the liver, heart, lung, brain, kidney and placenta. Deficiency in the ALDH5A1 enzyme, known as 4-hydroxybutyricaciduria, is a rare inborn error in the metabolism of the neurotransmitter 4-aminobutyric acid (GABA). In response to this defect, physiologic fluids from patients accumulate GHB, which is a compound with numerous neuromodulatory properties.

Peroxisomal 2,4-dienoyl-CoA reductase (DECR2) is an supporting enzyme of beta-oxidation. DECR2 partakes in the degradation of unsaturated fatty enoyl-CoA esters having double bonds in both even- and odd-numbered positions in peroxisome. DECR2 catalyzes the NADP-dependent reduction of 2,4-dienoyl-CoA to yield trans-3-enoyl-CoA.

Spermine synthase (SMS) is amember of the spermidine/spermine synthase family. SMS is an enzyme which converts spermidine into spermine. The SMS enzyme is essential for normal viability, growth and fertility involved in polyamine metabolism. Defects in the SMS gene are the cause of Snyder-Robinson syndrome (SRS), also known as X-linked mental retardation Snyder-Robinson type. SRS is categorized by moderate intellectual deficit, hypotonia, an unsteady gait, osteoporosis, kyphoscoliosis and facial asymmetry, its transmission is X-linked recessive.

ElaC Ribonuclease Z 1, also known as ELAC1 is a member of the RNase Z family. Zinc phosphodiesterase, which shows some tRNA 3'-processing endonuclease activity. In addition, ELAC1 is implicated in tRNA maturation, by removing a 3'-trailer from precursor tRNA.

Ornithine decarboxylase is the preliminary and rate-limiting enzyme in the biosynthetic pathway of polyamines and it takes part in the alteration of ornithine to putrescine. ODC1 is a key member of various biological processes, such as cell growth, transformation, differentiation and apoptosis. Overexpression of the ODC1 gene has a vital part in cell proliferation and the progress of cancer.

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.

FKBP6 is part of the immunophilin protein family, and is involved in immunoregulation and basic cellular functions involving protein folding and trafficking. FKBP6 is widely expressed in all tissues, FKBP6 is present at utmost levels in testis, liver, kidney, skeletal muscle and heart. Deletion of FKBP6 contributes to hypercalcemia and growth delay in Williams-Beuren syndrome.

Peptidase Inhibitor 16 (PI16) which a member of the CRISP family, is a putative serine protease inhibitor. PI16 interacts with PSP94/MSMB. PI16 is expressed in the prostate, testis, ovary and intestine. It also concentrates in prostate cancer patient's sera. PI16 may serve as a marker following prostatectomy for prostate cancer.

Phosphatidylinositol-5-Phosphate 4-Kinase, Type II, Beta (PIP4K2B) belongs to the phosphatidylinositol-4-phosphate 5-kinase family.PIP4K2B catalyzes the phosphorylation of phosphatidylinositol-4-phosphate on the 5th hydroxyl of the myo-inositol ring to form phosphatidylinositol-4,5-bisphosphate. PIP4K2B amino acid sequence does not show resemblance to another kinases although PIP4K2B presents kinase activity.PIP4K2B also interacts with p55 TNF receptor.

TKT is a thiamine-dependent enzyme that takes part in the channeling of leftover sugar phosphates to glycolysis in the pentose phosphate pathway. Multiple alternatively spliced variants are known that encode the same protein.

LPL is a lipoprotein lipase, which is expressed in the heart, muscle, and adipose tissue. LPL acts as a homodimer, and has the dual functions of triglyceride hydrolase and ligand/bridging factor for receptor-mediated lipoprotein uptake. Type I hyperlipoproteinemia is a result of severe mutations which cause LPL deficiency, whereas less extreme mutations in LPL are linked to many disorders of lipoprotein metabolism. Lipoprotein lipase (LPL) is a fundamental enzyme in plasma triglyceride hydrolysis and is secreted by macrophages in the subendothelial space. LPL also promotes the development of atherosclerosis through facilitation of monocyte adhesion to endothelial cells, stimulation of tumor necrosis factor alpha (TNF) secretion and induction of vascular smooth muscle cell proliferation.