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Human Ubc9 is homologous to ubiquitin-conjugating enzymes (E2s). However, instead of conjugating ubiquitin, it conjugates a ubiquitin homologue, small ubiquitin-like modifier 1(SUMO-1). And hUbc9 retains striking structural and functional conservation with yeast Ubc9. The ubiquitin-dependent protein degradation system has been recognized as a complete enzymatic pathway that is responsible for the selective degradation of abnormal and short-lived proteins. The conjugation of ubiquitin requires the activities of ubiquitin-activating (E1) and –conjugating (E2) enzymes.

PPIases catalyze the cis-trans isomerization of proline imidic peptide bonds in oligopeptides and accelerate the folding of proteins. Cyclophilin-A is a cyclosporin binding-protein and may play a role in cyclosporin A-mediated immunosuppression. Cyclophilin-A can also interact with several HIV proteins, including p55 gag, Vpr, and capsid protein, and has been shown to be necessary for the formation of infectious HIV virions. Multiple pseudogenes that map to different chromosomes have been reported.

GCDH is part of the acyl-CoA dehydrogenase family. GCDH is localized in the mitochondrial matrix as a homotetramer of 45-kD subunits. GCDH catalyzes the oxidative decarboxylation of glutaryl-CoA to crotonyl-CoA and CO(2) in the degradative pathway of L-lysine, L-hydroxylysine, and L-tryptophan metabolism. GCDH uses electron transfer flavoprotein as its electron acceptor.

Matrix metalloproteinases are a family of zinc and calcium-dependent endopeptidases that break down extracellular matrix proteins. The MMP9 is secreted as a 92kDa zymogen. Cleavage of ProMMP-9 results in the active enzyme, having a molecular weight of approximately 82kDa. MMP9 is composed of the following domains: a gelatin-binding domain consisting of three fibronectin type II units, a catalytic domain containing the zinc-binding site, a proline-rich type V collagen-homologous domain and a hemopexin-like domain. MMP9 is produced by the several cell types: monocytes, macrophages, neutrophils, keratinocytes, fibroblasts, osteoclasts and endothelial cells. MMP9 is involved in inflammatory responses, tissue remodeling, wound healing, tumor growth and metastasis. MMP9 may also play an important part in local proteolysis of the extracellular matrix and in leukocyte migration, as well as in bone osteoclastic resorption. MMP9 cleaves type IV and type V collagens into large C-terminal three quarter fragments and shorter N-terminal one quarter fragments. MMP9 can also degrade fibronectin but not laminin or Pz-peptide.
MMP9 defects may be a cause of susceptibility to intervertebral disc disease (IDD), also known as lumbar disk herniation (LDH).

6PGD is the 2nd dehydrogenase in the pentose phosphate shift. Pentose is crucial for the biosynthesis of nucleic acid. The pentose phosphate cycle is a prominent source of NADPH. 6PGD deficiency is mostly asymptomatic, and the inheritance of this deasis is autosomal dominant. PGD deficiency elevate the erythrocyte pyruvate kinase levels of activity & decreases glutathione synthetase, which causes hemolysis.

GGCT is a member of the family of transferases, specifically the aminoacyltransferases. GGCT protein catalyzes the formation of 5-oxoproline from gamma-glutamyl dipeptides and takes an important part in glutathione homeostasis. GGCT induces release of cytochrome c from mitochondria with resultant induction of apoptosis.

MDH2 catalyzes the reversible oxidation of malate to oxaloacetate, utilizing the NAD/NADH cofactor system in the citric acid cycle. MDH2 is localized to the mitochondria and takes part in the malate-aspartate shuttle that functions in the metabolic coordination between cytosol and mitochondria. MDH2 is highy expressed in the adrenal system, small intestine, heart and pancreas.

Elongator acetyltransferase complex subunit 5 (ELP5) is a member of the ELP5 family. ELP5 functions as subunit of the RNA polymerase II elongator complex, which is a histone acetyltransferase component of the RNA polymerase II (Pol II) holoenzyme and is participated in transcriptional elongation. Elongator plays a role in chromatin remodeling and is involved in acetylation of histones H3 and probably H4. ELP5 takes part in cell migration and is widely expressed in in heart, brain, liver, skeletal muscle and testis.

E3 ubiquitin-protein ligase RNF181 (RNF181) accepts ubiquitin from an E2 ubiquitin-conjugating enzyme in the thioester form and subsequently directly transfers the ubiquitin to targeted substrates. RNF181 is widely expressed, with the highest levels in the liver and heart and the lowest levels in the brain and skeletal muscle. RNF181 is also expressed in platelets (at protein level).

SAT-1 is a member the acetyltransferase family, and is a rate-limiting enzyme in the catabolic pathway of polyamine metabolism. SAT1 catalyzes the acetylation of spermidine and spermine, and is involved in the regulation of the intracellular concentration of polyamines and their transport out of cells. Therefore, SAT-1’s role is essential in polyamine homoeostasis, given that acetylated products are either excreted from the cell or oxidized by acetylpolyamine oxidase. Increased SAT1 activity causes variety of other effects which include pancreatic cells death, obstruction of regenerative tissue growth, behavioral changes, keratosis follicularis spinulosa decalvans (KFSD), and hair loss.
Defects in the SAT1 gene are linked to KFSD (keratosis follicularis spinulosa decalvans), which is a rare X-linked disorder affecting the skin and the eye. The KFSD affected men show thickening of the skin of the neck, ears, and extremities, particularly the palms and soles, loss of eyebrows, eyelashes and beard, thickening of the eyelids with blepharitis and ectropion, and corneal degeneration. Even though the majority of the affected families are compatible with an X-linked inheritance, KFSD are found to be clinically and genetically heterogeneous.

Iduronate 2-Sulfatase also known as IDS, belongs to the highly-conserved sulfatase family of enzymes which catalyze the hydrolysis of O-sulfate and N-salfate esters from a variety of substrates. IDS is essential for the lysosomal degradation of the glycosaminoglycans (GAG) heparan sulfate as well as dermatan sulfate. Furthermore, IDS hydrolyzes the 2-sulfate group of the IDS units of the GAG.

AHCY is an enzyme that catalyzes the reversible hydrolysis of S-adenosylhomocysteine (AdoHcy) to adenosine (Ado) and L-homocysteine (Hcy). AHCY controls the intracellular S-adenosylhomocysteine (SAH) concentration that is crucial for transmethylation reactions. AHCY deficiency causes hypermethioninemia.

PI3Ka plays a specific role in apoptosis in human colon cancer cells. Injection of neutralizing antibodies specific to PI3Ka into adenocarcinoma cells induced apoptosis, a response that was reverted by treating cells with caspase inhibitor. It was also shown that PI3Ka mediated phosphorylation of the p85a adapter reduces the lipid kinase activity of the heterodimer and this gives hints for PI3K-dependent signaling events not requiring production of 3’-phosphorylated phosphoinositides.
PI3Ka is a key regulator of the initiation of keratinocyte differentiation. A decrease in PI3Ka activity results in a loss of keratinocyte adhesion to the extracellular membrane and the initiation of early phase differentiation.

Alcohol dehydrogenase 6 (ADH6) belongs to the alcohol dehydrogenase family. Alcohol dehydrogenase family members metabolize a wide variety of substrates, including ethanol, retinol, other aliphatic alcohols, hydroxysteroids, and lipid peroxidation products. ADH6 is expressed in the stomach as well as in the liver, and it contains a glucocorticoid response element upstream of its 5’ UTR, which is a steroid hormone receptor binding site.

THTPA enzyme is part of the THTPase family. THTPA is localized to the cytoplasm and expressed at small quantities in a variety of tissues, including testis, uterus, prostate, bladder, lung and kidney. THTPA is a hydrolase that catalyzes the H2O-dependent hydrolysis of thiamine triphosphate (THTP) to thiamine diphosphate (THDP), the main form of thiamine within the cell. THTPA occurs as a monomer and is activated at an optimal pH of 8.5.

Thiosulfate sulfurtransferase like domain containing 1 (TSTD1) is a member of a family of transferases, specifically the sulfurtransferases, which transfer sulfur-containing groups. TSTD1 is localized around the nuclear membranes. TSTD1 is expressed in a number of human tissues, including the kidney, liver, skeletal muscle, heart, colon, thymus, spleen, placenta and lung. TSTD1 may participate in cyanide detoxification, the formation of iron-sulfur proteins, and the modification of sulfur-containing enzymes.

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.

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.

RANKL binds to tnfrsf11b/opg and to tnfrsf11a/rank. Osteoclast differentiation and activation factor. Augments the ability of dendritic cells to stimulate naive t-cell proliferation. May be an important regulator of interactions between t-cells and dendritic cells and may play a role in the regulation of the t-cell-dependent immune response. sRANKL may also play an important role in enhanced bone-resorption in humoral hypercalcemia of malignancy.

ADH1C is a member of the zinc-containing alcohol dehydrogenase family which metabolizes a large assortment of substrates, such as ethanol, retinol, other aliphatic alcohols, hydroxysteroids, and lipid peroxidation products. ADH1 is a monomorphic and a key factor in fetal and infant livers, becoming less active in gestation and only weakly active during adulthood.

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.

Ecto-ADP-Ribosyltransferase 4 or ART4 is typed as a glycosylphosphatidylinositol (GPI)-linked membrane protein which carries Dombrock blood group antigens. The development of this protein takes place at the highest levels in the fetal liver. the process of the ART4 development is regulated while the erythroid differentiation process occurs. ART4 is a is part of the Ribosyltransferase family.

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.

TIE-1 (tyrosine kinase with Ig and EGF homology domains 1) and TIE-2/Tek comprise a receptor tyrosine kinase (RTK) subfamily with unique structural characteristics: two immunoglobulin-like domains flanking three epidermal growth factor (EGF)-like domains and followed by three fibronectin type III-like repeats in the extracellular region and a split tyrosine kinase domain in the cytoplasmic region. These receptors are expressed primarily on endothelial and hematopoietic progenitor cells and play critical roles in angiogenesis, vasculogenesis and hematopoiesis. Human TIE-1 cDNA encodes a 1122 amino acid (aa) residue precursor protein with an 18 residue putative signal peptide, a 726 residue extracellular domain and a 353 residue cytoplasmic domain. Two ligands, angiopoietin-1 (Ang1) and angiopoietin-2 (Ang2), which bind TIE-2 with high-affinity have been identified. Ang2 has been reported to act as an antagonist for Ang1. Mice engineered to overexpress Ang2 or to lack Ang1 or Tie-1 display similar angiogenic defects.