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Ectonucleotide Pyrophosphatase-2, aka ENPP2, a part of the ectonucleotide pyrophosphatasefamily. ENPP2 is able to cut the phosphodiester bond between the alpha and the beta position of triphosphate nucleotides, acting as an ectonucleotide phosphodiesterase producing pyrophosphate, as most members of the ENPP family. It is unlike ENPP-1 and ENPP-3, has weak activity against nucleotides, but shows a lysophospholipase D activity which allows the formation of LPA and choline from lysophosphatidylcholine. As well, ENPP-2 and LPA are involved in several inflammatory-driven diseases such as arthritis and asthma.

Protein Tyrosine Phosphatase Type IVA Member 3 (PTP4A3) is a member of a small class of prenylated protein tyrosine phosphatases (PTPs) which remove phosphate modifications from tyrosine residues on proteins. PTP4A3 enhances cell proliferation, cell motility and invasive activity. PTP4A3 functions as a protein tyrosine phosphatase which stimulates progression from G1 into S phase during mitosis. PTP4A3 is mostly expressed in cardiomyocytes and skeletal muscle; it is also found in the pancreas.
PTP4A3 is always overexpressed in colon cancer metastasis. PTP4A3 is notably overexpressed in liver metastasis of colorectal cancer. High levels of PTP4A3 expression are linked to tumorigenesis and metastasis; therefore it is overexpressed in metastatic colorectal, ovarian, liver and skin cancers. PTP4A3 may be involved in the progression of cardiac hypertrophy by inhibiting intracellular calcium mobilization in response to angiotensin II. PTP4A3 is inhibited by sodium orthovanadate and peroxovanadium compounds.

Fructose-1,6-bisphosphatase isozyme 2 (FBP2) is a part of the FBPase class 1 family. FBP2 is a gluconeogenesis regulatory enzyme Which catalyzes the hydrolysis of fructose 1,6-bisphosphate to fructose 6-phosphate and inorganic phosphate.

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.

Astyrosine-protein phosphatase non-receptor type 11 isoform 2 (PTPN11), is a member of the protein-tyrosine phosphatase family, non-receptor class 2 subfamily. PTPN11 takes part in signal transduction from the cell surface to the nucleus downstream of various cytosolic protein tyrosine kinases as well as receptors. PTPN11 deficient cells have poor mobility due to excessive phosphorylation of FAK as well as other proteins which interfere with the rotation of cell attachment points in the focal adhesion complex.

DUSP3 belongs to the dual specificity protein phosphatase subfamily which inactivates their target kinases by dephosphorylating both the phosphoserine/threonine and phosphotyrosine residues. DUSP3 negatively regulate members of the mitogen-activated protein kinase superfamily that are related to cellular proliferation and differentiation. DUSP3 is expressed in both breast and ovarian tissues and displays activity both for tyrosine-protein phosphate and serine-protein phosphate, but exhibits a strong preference toward phosphotyrosines, specifically dephosphorylates and inactivates ERK1 and ERK2.

RNA Guanylyltransferase And 5'-Phosphatase also known as RNGTT is a bifunctional mRNA-capping enzyme which exhibits RNA 5'-triphosphatase activity in the N-terminal section and mRNA guanylyltransferase activity in the C-terminal section. In addition, RNGTT catalyzes the first two steps of cap formation, through removing the gamma-phosphate from the 5'-triphosphate end of nascent mRNA to yield a diphosphate end, and also by transferring the gmp moiety of GTP to the 5'-diphosphate terminus.

N-acylneuraminate-9-phosphatase (NANP) belongs to the haloacid dehalogenase (HAD) family and is responsible for dephosphorylating N-acylneuraminate 9-phosphate to form N-acylneuraminate (N-acylneuraminate 9-phosphate + H2O = N-acylneuraminate + phosphate). The catalytic activity of NANP is relies on the presence of magnesium and is inhibited by vanadate and calcium, which is typical of the HAD phosphatase family.

DCTPP1, also known as dCTP pyrophosphatase 1, contains an epilepsy-associated repeat (EAR) domain that is predicted to participate in protein-protein interactions, most likely involved in ligand recognition. This protein functions to hydrolyze abnormal nucleotide triphosphates (NTPs) in cancer cells that, if unregulated, could be incorporated into nascent DNA or RNA.

SSU72 is an extremely conserved homologue of yeast Ssu72, a CTD phosphatase and a component of the polyadenylation/termination machinery. SSU72 interacts with TFIIB, Rb and DNAM-1 and operates to catalyze the dephosphorylation of target proteins, and taking part in RNA processing and termination via dephosphorylation of Pol II. SSU72 is found in multiple alternatively spliced isoforms.

Protein tyrosine phosphatase type IVA 1 (PTP4A1) is a cell signaling molecule that has regulatory roles in a variety of cellular processes. PTP4A1 is a unique nuclear PTP which is induced in regenerating liver and mitogen stimulated cells. PTP4A1 is primarily expressed in the spleen, bone marrow, thymus, lymph nodes, T lymphocytes and tonsil and is overexpressed in tumor cell lines.

ITPA enzyme catalyzes the pyrophosphohydrolysis of both ITP (inosine triphosphate) and dITP (deoxyinosine triphosphate) to IMP (inosine monophosphate) and diphosphate. IMP is exercised as a substrate for purine nucleotide pathways. IMP is phosphorylated to ITP, and ITPA mediates the concentration of ITP in the cell by changing ITP back to IMP. Defects in ITPA result in ITPA deficiency which is thought to be inherited and is characterized by an over-accumulation of ITP in erythocytes, leukocytes and fibroblasts.

FBP1 or Fructose-1, 6-bisphosphatase 1 is an enzyme, catalyzing the formation of fructose 6-phosphate & inorganic phosphate from fructose 1, 6-bisphosphate. FBP1 is part of the gluconeogenesis regulatory enzymes. Mutations in the enzyme gene can result in metabolic acidosis & hypoglycemia.

PTPN6 is a member of the protein tyrosine phosphatase (PTP) family. PTPs are known to be signaling molecules that regulate a variety of cellular processes including cell growth, differentiation, mitotic cycle, and oncogenic transformation. N-terminal part of this PTP contains two tandem Src homolog (SH2) domains, which act as protein phospho-tyrosine binding domains, and mediate the interaction of this PTP with its substrates. This PTP is expressed primarily in hematopoietic cells, and functions as an important regulator of multiple signaling pathways in hematopoietic cells. This PTP has been shown to interact with, and dephosphorylate a wide spectrum of phospho-proteins involved in hematopoietic cell signaling. Multiple alternatively spliced variants of this gene, which encode distinct isoforms, have been reported.

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.

ACP1 is part of the phosphotyrosine protein. ACP1 functions as an acid phosphatase and a protein tyrosine phosphatase (PTPase) existing in all human tissues, including adipocytes. ACP1 enzyme hydrolyzes protein tyrosine phosphate to protein tyrosine and orthophosphate, and also orthophosphoric monoesters to alcohol and orthophosphate. ACP1 is present in adipocytes, thus playing a specific role in the regulation of adipose tissue. High levels of the ACP1 negatively regulate cell proliferation and growth of leiomyomas during dephosphorylation of the PDGF receptor. High significant differences in birth weight-placental weight relationships were observed among acid phosphatase locus 1 phenotypes.

PPME1 catalyzes the demethylation and inactivation of protein phosphatase (PP2A), a multimeric phosphoserine/ threonine protein phosphatase related to growth inhibition and cell cycle arrest. PPME1 can demethylate PP2A catalytic subunit in vitro and okadaic acid treatment can inhibit this reaction. It is conserved from yeast to human and holds a motif found in lipases having a catalytic triad activated serine as their active site nucleophile.

PTEN, a tumor suppressor, has been implicated in a large number of human tumors and is conserved from humans to worms. PTEN has a tensin like domain and a catalytic domain similar to that of the dual specificity protein tyrosine phosphatases. Characterization of PTEN protein showed that it is a phosphatase that acts on proteins and on 3-phosphorylated phosphoinositides, and can therefore modulate signal transduction pathways that involve lipid second messengers. In contrast to most of the protein tyrosine phosphatases, PTEN preferentially dephosphorylates phosphoinositide substrates. PTEN negatively regulates intracellular levels of phosphatidylinositol-3,4,5-trisphosphate in cells and acts as a tumor suppressor by negative regulation of AKT/PKB signaling pathway. Recent results indicate that at least part of its role is to regulate the activity of the serine/threonine kinase AKT/PKB, and thus influence cell survival signaling.

IMPA2 is a member of the inositol monophosphatase family. IMPA2 catalyzes the dephosphoylration of inositol monophosphate and has a significant role in phosphatidylinositol signaling. IMPA2 can use the myo-inositol monophosphates, scylloinositol 1,4-diphosphate, glucose-1-phosphate, beta-glycerophosphate, and 2'-AMP as substrates. IMPA2 is a pharmacological target for lithium Li(+) action in brain. IMPA2 is considered to have a role in schizophrenia and bipolar disorder.

PPM1G is part of the PP2C family of Ser/Thr protein phosphatases which are known to be negative regulators of cell stress response pathways. PPM1G is accountable for the dephosphorylation of Pre-mRNA splicing factors, an important factor for the formation of functional spliceosome. PPM1G regulates cell cycle progression. PPM1G mediates histone dephosphorylation/exchange in response to DNA damage or checkpoint recovery in higher eukaryotes. The degradation of p21/WAF1 induced by PPM1G is mediated in a proteasome-dependent manner. Protein phosphatase 1G regulates assembly and function of the beta-catenin degradation complex.

PPME1 catalyzes the demethylation and inactivation of protein phosphatase (PP2A), a multimeric phosphoserine/ threonine protein phosphatase related to growth inhibition and cell cycle arrest. PPME1 can demethylate PP2A catalytic subunit in vitro and okadaic acid treatment can inhibit this reaction. It is conserved from yeast to human and holds a motif found in lipases having a catalytic triad activated serine as their active site nucleophile.

Protein Phosphatase 2C alpha is a member of the PP2C family of Ser/Thr protein phosphatases. PP2C family members are known to be negative regulators of cell stress response pathways. This phosphatase dephosphorylates, and negatively regulates the activities of, MAP kinases and MAP kinase kinases. It has been shown to inhibit the activation of p38 and JNK kinase cascades induced by environmental stresses. This phosphatase can also dephosphorylate cyclin-dependent kinases, and thus may be involved in cell cycle control. Overexpression of this phosphatase is reported to activate the expression of the tumor suppressor gene TP53/p53, which leads to G2/M cell cycle arrest and apoptosis. Three alternatively spliced transcript variants encoding two distinct isoforms have been described. Protein phosphatase 2C(PP2Cα) is a Mn2+- or Mg2+-dependent protein serine/threonine phosphatase that is essential for regulating cellular stress response in eukaryotes.

Ectonucleotide Pyrophosphatase (ENPP1) belongs to the ecto-nucleotide pyrophosphatase/phosphodiesterase (ENPP) family. ENPP1 is a type II transmembrane glycoprotein comprised of 2 identical disulfide-bonded subunits. The ENPP1 protein has broad specificity and cleaves various substrates, including phosphodiester bonds of nucleotides and nucleotide sugars and pyrophosphate bonds of nucleotides and nucleotide sugars. The ENPP1 protein can hydrolyze nucleoside 5' triphosphates to their corresponding monophosphates and it may also hydrolyze diadenosine polyphosphates. ENPP1 gene mutations are linked with 'idiopathic' infantile arterial calcification and ossification of the posterior longitudinal ligament of the spine (OPLL).