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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.

Formiminotransferase cyclodeaminase is an enzyme which catalyzes the conversion of formiminoglutamateand tetrahydrofolateinto formiminotetrahydrofolateand glutamate.
Formiminotransferase cyclodeaminase, a bifunctional enzyme of tetrahydrofolate synthesis, is the target antigen of anti-LC1 (liver cytosol antigen type 1) autoantibodies. Presence of LC1 autoantibodies is a marker for type 2 autoimmune hepatitis (for which anti-LKM 1/cytochrome P450 2D6 autoantibodies are a further marker).
Serum LC1 autoantibody concentrations appear to fluctuate in parallel with aminotransferase levels, a particularly intriguing observation that suggests a possible role of LC1 autoreactivity in the pathogenic mechanism leading to hepatocyte injury.

Pin 1 is a peptidyl-prolyl cis/trans isomerase (PPIase) which interacts with NIMA and essential for cell cycle regulation Pin1 is nuclear PPIase containing a WW protein interaction domain, and is structurally and functionally related to Ess1/Ptf1, an essential protein in budding yeast. PPIase activity is necessary for Ess1/Pin1 function in yeast. Pin1 is thus an essential PPIase that regulates mitosis presumably by interacting with NIMA and attenuating its mitosis-promoting activity. Substrates of Pin1 include the mitotic regulators (Cdc25 phosphatase and NIMA, PLK I, Wee, and Myt1 kinases), several transcription factors like b-Catenin, c-Jun, and the tumor suppressor protein p53, and some specific proteins like the RNA Pol II, the cytoskeleton protein tau, and the G1/S protein Cyclin D1.

Cathepsin-Z (CTSZ) is a lysosomal cysteine proteinase and member of the peptidase C1 family. CTSZ, which has been also known as cathepsin X and cathepsin P, exhibits carboxy-monopeptidase and carboxy-dipeptidase activities. CTSZ is expressed ubiquitously in cancer cell lines and primary tumors and, similar to other members of this family, takes part in tumorigenesis.

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.

SAE1 and SAE2 form heterodimers which take part in the posttranslational modification of proteins (sumoylation). This process regulates protein structure as well as intracellular localization of the target. SAE1/SAE2 may indicate on dermatomyositis (DM) as autoantibodies against those 2 proteins have been found in patients.

NUDT10 belongs to the Nudix hydrolase family of pyrophosphatases. Nudix hydrolases contain a characteristic Nudix domain and are responsible for catalyzing the hydrolysis of nucleoside diphosphate derivatives. NUDT10 functions as a manganese-dependent polyphosphate phosphohydrolase with an optimum pH of 8.5. NUDT10 protein specifically metabolizes diadendosine-polyphosphates and, to a lesser extent, diphosphoinositol polyphosphates.

Phospholipase A2 (PLA2) catalyzes the hydrolysis of the sn-2 position of membrane glycerophospholipids to liberate arachidonic acid (AA), a precursor of eicosanoids including prostaglandins and leukotrienes. The same reaction also produces lysophosholipids, which represent another class of lipid mediators.
The secretory PLA2 (sPLA2) family, in which 10 isozymes have been identified, consists of low molecular weight, Ca2+-requiring secretory enzymes that have been implicated in a number of biological processes, such as modification of eicosanoid generation, inflammation, and host defense.
This enzyme has been proposed to hydrolyze phosphatidylcholine (PC) in lipoproteins to liberate lyso- PC and free fatty acids in the arterial wall, thereby facilitating the accumulation of bioactive lipids and modified lipoproteins in atherosclerotic foci.
In mice, sPLA2 expression significantly influences HDL particle size and composition and demonstrate that an induction of sPLA2 is required for the decrease in plasma HDL cholesterol in response to inflammatory stimuli. Instillation of bacteria into the bronchi was associated with surfactant degradation and a decrease in large:small ratio of surfactant aggregates in rats.

QDPR belongs to the short-chain dehydrogenases/reductase (SDR) family of enzymes. Operating as a homodimer, QDPR has an imperative role in the recycling of tetrahydrobiopterin (BH4), a vital cofactor for the hydroxylation of the aromatic amino acids (tryptophan, tyrosine and phenylalanine). More precisely, QDPR catalyzes the regeneration of BH4 from quinonoid dihydrobiopterin (qBH2), the product generated from the hydroxylation reactions. Mutations in the QDPR gene may lead to phenylketonuria II.

NQO1 belongs to the NAD(P)H dehydrogenase (quinone) family and encodes a cytoplasmic 2-electron reductase. NQO1 acts as an imperative part of cellular antioxidant defense by detoxifying quinines therefore preventing the formation of reactive oxygen species. It seems that NQO1 serves as a quinone reductase relating to conjugation reactions of hydroquinons involved in detoxification pathways in addition to biosynthetic processes such as the vitamin K-dependent gamma-carboxylation of glutamate residues in prothrombin synthesis. Altered NQO1 expression is seen in many tumors and also linked to Alzheimer’s disease. NQO1 gene mutations are linked to tardive dyskinesia which is an increased risk of hematotoxicity after exposure to benzene, and susceptibility to various forms of cancer.

GSTM4 is part of the glutathione s-transferase (GST) family of proteins. There are eight families of GST proteins, namely alpha, kappa, mu, omega, pi, sigma, theta and zeta, each of which is composed of proteins that have a variety of functions throughout the cell. The mu class of enzymes functions in the detoxification of electrophilic compounds, including carcinogens, therapeutic drugs, environmental toxins and products of oxidative stress, by conjugation with glutathione.

UPP1 catalyzes the reversible phosphorylytic cleavage of uridine and deoxyuridine to uracil and ribose- or deoxyribose-1-phosphate which are used as carbon and energy sources or in the release of pyrimidine bases for nucleotide synthesis. UPP1 is part of the family of glycosyltransferases, specifically the pentosyltransferases. Pyrimidine nucleoside phosphorylases add ribose or deoxyribose to pyrimidine bases to form nucleosides that can be incorporated into RNA or DNA.

Ubiquitin-Conjugating Enzyme E2G2 (UBE2G2) is a protein coding gene which is a part of the E2 ubiquitin-conjugating enzyme family. UBE2G2 accepts ubiquitin from the E1 complex and catalyzes its covalent attachment to various proteins. UBE2G2 is ubiquitously expressed mainly in adult muscle. UBE2G2 also takes part in endoplasmic reticulum-associated degradation (ERAD).

DNA polymerase beta (POLB) is a member of the DNA polymerase type-X family. In eukaryotic cells, POLB performs base excision repair necessary for DNA maintenance, replication, recombination, and drug resistance. POLB has 2 separate domains; the larger is the polymerase domain itself, whereas a small basic N-terminal domain contains an AP lyase activity which excises the abasic sugar-phosphate residue at the strand break. POLB fills single nucleotide gaps in DNA produced by the base excision repair pathway of mammalian cells. POLB overexpression, as seen in some human tumors, could convene an increase in spontaneous mutagenesis.

NEDD8-activating enzyme E1 catalytic subunit (UBA3) is the catalytic subunit of the dimeric UBA3-NAE1 E1 enzyme, which belongs to the E1 ubiquitin-activating enzyme family. E1 activates NEDD8 by initially adenylating its C-terminal glycine residue with ATP, afterwards linking this residue to the side chain of the catalytic cysteine, generating a NEDD8-UBA3 thioester and free AMP. E1 at last transfers NEDD8 to the catalytic cysteine of UBE2M. The UBA3 enzyme connects with AppBp1, an amyloid beta precursor protein binding protein, to form a heterodimer, and at that point the enzyme complex activates NEDD8, a ubiquitin-like protein, which controls cell division, signaling and embryogenesis.

Adenosine Kinase is an abundant enzyme in mammalian tissues which catalyzes the transfer of the gamma-phosphate from ATP to adenosine, thus is as a regulator of concentrations of both extracellular adenosine and intracellular adenine nucleotides. Adenosine has extensive effects on the cardiovascular, nervous, respiratory, and immune systems and inhibitors of the enzyme take a crucial pharmacological part in growing intravascular adenosine concentrations and acting as anti-inflammatory agents.

Cas9 (CRISPR associated protein 9) is an RNA-guided DNA endonuclease enzyme associated with the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) adaptive immunity system in Streptococcus pyogenes, among other bacteria. S. Pyogenes utilizes Cas9 to remember and later probe and cleave foreign DNA, such as invading bacteriophage DNA or plasmid DNA. In case that the DNA substrate is complementary to the guide RNA, Cas9 cleaves the invading DNA. In addition to its original role in bacterial immunity, the Cas9 protein has been heavily employed as a genome engineering tool to induce site-directed double strand breaks in DNA. These disruptions may lead to gene inactivation or the presentation of heterologous genes via non-homologous end joining and homologous recombination respectively in many laboratory model organisms.

LYPLA1 is lysophospholipase which performs on biological membranes to regulate the multifunctional lysophospholipids. LYPLA1 protein hydrolyzes fatty acids from S-acylated cysteine residues in proteins like trimeric G alpha proteins or HRAS and in addition has depalmitoylating activity.

POLR2J2 belongs to the RNA polymerase II subunit 11 gene family, that includes 3 genes in a cluster on chromosome 7q22.1 and a pseudogene on chromosome 7p13. DNA directed RNA polymerase II polypeptide J family encodes a subunit of RNA polymerase II, the polymerase which is responsible for synthesizing messenger RNA in eukaryotes. This locus produces multiple, otherwise spliced transcripts which express isoforms with distinct C-termini compared to DNA directed RNA polymerase II polypeptide J. Most or all variants are spliced to include additional non-coding exons at the 3' end that makes them candidates for nonsense-mediated decay (NMD). Therefore, it is unknown if this locus expresses a protein or proteins in vivo.

REXO1 is an exonuclease domain-containing protein which binds to Elongin. The Elongin complex stimulates the rate of transcription elongation by RNA polymerase II by suppressing the transient pausing of the polymerase at many sites along the DNA template. REXO1 is composed of 1221 amino acids and its mRNA is ubiquitously expressed. REXO1 is a putative stem cell marker and is highly expressed in embryonic and adult stem cells.

Creatine Kinase MM is a cytoplasmic enzyme involved in energy homeostasis and is an important serum marker for myocardial infarction. The encoded protein reversibly catalyzes the transfer of phosphate between ATP and various phosphogens such as creatine phosphate. It acts as a homodimer in striated muscle as well as in other tissues, and as a heterodimer with a similar brain isozyme in heart. The encoded protein is a member of the ATP:guanido phosphotransferase protein family.

SEPSECS catalyzes the last step of sec synthesis by 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.

GSTT2 belongs to the glutathione s-transferase (GST) family of proteins. There are eight GST proteins families, named alpha, kappa, mu, omega, pi, sigma, theta and zeta. Each one of the GST families has several proteins with different functions throughout the cell. The theta type members GSTT1 and GSTT2 have a 55% aa sequence homology and hold a vital role in human carcinogenesis. The theta genes are structurally similar – each has five exons with identical exon/intron boundaries.