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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.

DUSP10 is a member of the protein-tyrosine phosphatase family. DUSPs inactivate their target kinases by dephosphorylating both the phosphoserine/threonine and phosphotyrosine residuesb and negatively regulate members of the MAPK superfamily which is linked with cellular proliferation and differentiation. DUSP10 interacts with MAPK14 and MAPK8. DUSP10 blocks in mammalian cells the enzymatic activation of MAP kinases with the selectivity p38 approximately JNK/SAPK >> ERK.

Dual Specificity Phosphatase 22, also known as DUSP22, is a part of the protein-tyrosine phosphatase family which holds 1 tyrosine-protein phosphatase domain. DUSP22 activates the Jnk signaling pathway and dephosphorylates and deactivates p38 and stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK). DUSP22 interacts with MAPK1 and MAPK8.

PHOSPHO1 is involved in mineralization process & plays a role in bone and cartilage matrix mineralization.
PHOSPHO1 is expressed at sites of mineralization in bone and cartilage. Highly expressed in osteoblast cell line SaOS-2 which produces a mineralized matrix.
Orphan-1 is collagen type -2 is specific for cartilaginous tissues. Orphan1 is essential for the normal embryonic development of the skeleton, for linear growth and for the ability of cartilage to resist compressive forces.
Phosphoethanolamine (2-O3POCH2CH2NH3) is a key intermediate in the formation of cephalins, it is formed in liver and brain by phosphorylation of ethanolamine.
PHOSPHO2 and PHOSPHO1 suggest subtle differences in the charge distributions around the putative substrate entry site and in the location of potential H-bond donors.
PHOSPHO1 exhibits high specific phosphoethanolamine and phosphocholine phosphatase activities PHOSPHO1 is a phosphatase enzyme for which expression is upregulated in mineralizing cells. PHOSPHO1 has been implicated in the generation of Pi for matrix mineralization, a process central to skeletal development. PHOSPHO1 is a member of the haloacid dehalogenase (HAD) superfamily of Mg2+-dependent hydrolases. PHOSPHO1 exhibits high specific activities toward phosphoethanolamine (PEA) and phosphocholine (PCho).

Dual specificity phosphatase 18 (DUSP18) belongs to the dual-specificity phosphatase (DSP) family, which catalyzes dephosphorylation of phosphotyrosine and phosphothreonine residues. DUSP18 has a preferential enzymatic activity for phosphorylated tyrosine residues over threonine residues, in addition DUSP18 dephosphorylates p-nitrophenyl phosphate (pNPP) in vitro. Furthermore, DUSP18 is inhibited by iodoarectic acid and is activated by manganese ions. DUSP18 is extensively expressed with the highest levels in the liver, brain, ovary and testis.

Prostatic acid phosphatase, also known as PAP, is an enzyme produced by the prostate. PAP may be found in increased amounts in men with prostate cancer.
PAP’s physiological function may be associated with the liquefaction process of semen.
The highest levels of PAP are found in metastasized prostate cancer. Diseases of the bone, such as Paget's disease or hyperparathyroidism, diseases of blood cells (sickle-cell disease) or multiple myeloma or lysosomal storage diseases (Gaucher's disease), will show moderately higher levels.
Certain medications can cause temporary changes in PAP levels. Manipulation of the prostate gland through rectal exam, biopsy or massage may increase the level.

DUSP23 is a member of the protein-tyrosine phosphatase family. DUSP23 is a protein phosphatase which facilitates dephosphorylation of phosphorylated proteins on Tyr and Ser/Thr residues. In vitro, DUSP23 dephosphorylate p44-ERK1 (MAPK3) but not p54 SAPK-beta (MAPK10). In addition, DUSP23 enhances activation of JNK and p38(MAPK14).

Protein Tyrosine Phosphatase Non Receptor Type-4, also known asPTPN4 belongs to the protein tyrosine phosphatase, PTP family. PTPs are identified as signaling molecules which regulate a variety of cellular processes as well as cell growth, differentiation, mitotic cycle, and oncogenic transformation. PTPN4 is broadly expressed non-receptor protein tyrosine phosphatase. In addition, PTPN4 interacts with glutamate receptor delta 2 & epsilon, and affects glutamate receptors signaling and/or in regulation of their activities through tyrosine dephosphorylation.

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(PP2C?) is a Mn2+- or Mg2+-dependent protein serine/threonine phosphatase that is essential for regulating cellular stress response in eukaryotes.

Pyridoxal phosphate phosphatase PHOSPHO2, orphan 2 (PHOSPHO2) is a member of the haloacid dehalogenase (HAD) superfamily. Phosphatase has an elevated activity toward phosphoethanolamine (PEA) and phosphocholine (PCho). PHOSPHO 1, a phosphoethanolamine/phosphocholine phosphatase, is upregulated in mineralizing cells and is believed to be implicated in the production of inorganic phosphate for bone mineralization. PHOSPHO2 is a recognized phosphatase sharing a 42% sequence identity with PHOSPHO1. PHOSPHO1 and PHOSPHO2 are especially similar, however surprisingly recombinant PHOSPHO2 hydrolyses phosphoethanolamine and phosphocholine comparatively inadequately.

Prostatic Acid Phosphatase or ACPP is part of a family of proteins called histidine acid phosphatase. ACPP enhances the hydrolyzation of many phosphate monoesters and proteins that are phosphorylated. In order to function best, ACPP needs a range of range of 4-6 pH, furthermore, L(+)-tartrate inhibits ACPP’s catalyzation. This enzyme can act as a lipid phosphatase as well and can inhibit lysophosphatidic acid in seminal plasma.

Acid phosphatase, prostate (ACPP) is a non-specific tyrosine phosphatase, which dephosphorylates a varied number of substrates under acidic conditions (pH 4-6) including alkyl, aryl, and acyl orthophosphate monoesters and phosphorylated proteins. ACPP has lipid phosphatase activity and inactivates lysophosphatidic acid in seminal plasma.

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.

DUSP23 is a member of the protein-tyrosine phosphatase family. DUSP23 is a protein phosphatase which facilitates dephosphorylation of phosphorylated proteins on Tyr and Ser/Thr residues. In vitro, DUSP23 dephosphorylate p44-ERK1 (MAPK3) but not p54 SAPK-beta (MAPK10). In addition, DUSP23 enhances activation of JNK and p38(MAPK14).

PTPN7 performs specifically on tyrosine-phosphorylated MAPK1. PTPN7 takes part in the regulation of signal transduction and T and B-lymphocyte development.

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.

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.

Protein Tyrosine Phosphatase 1B is the founding member of the protein tyrosine phosphatase (PTP) family, which was isolated and identified based on its enzymatic activity and amino acid sequence. PTPs catalyze the hydrolysis of the phosphate monoesters specifically on tyrosine residues. Members of the PTP family share a highly conserved catalytic motif, which is essential for the catalytic activity. PTPs are known to be signaling molecules that regulate a variety of cellular processes including cell growth, differentiation, mitotic cycle, and oncogenic transformation. This PTP has been shown to act as a negative regulator of INS signaling by dephosphorylating the phosphotryosine residues of INS receptor kinase. This PTP was also reported to dephosphorylate epidermal growth factor receptor kinase, as well as JAK2 and TYK2 kinases, which implicated the role of this PTP in cell growth control, and cell response to IFN stimulation.

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.

PPP1CC is vital for cell division and takes part in the regulation of protein synthesis, muscle contractility and glycogen metabolism. Additionally, PPP1CC has a role in long-term synaptic plasticity and regulation of ionic conductance, and has a significant role in dephosphorylating substrates such as the postsynaptic density-associated Ca2+/calmodulin dependent protein kinase II.

Magnesium-dependent phosphatase 1 (MDP1) is a memeber of the HAD-like hydrolase superfamily. MDP1 is a magnesium-dependent phosphatase which may act as a tyrosine phosphatase. MDP1 is inhibited by vanadate and zinc, and slightly by calcium.

Placental alkaline phosphatase also known as PLAP is a membranal siaglycoprotein enzyme typicallyfoundin high concentration in syncytiotrophoblasts in the placenta amid the 3th trimester of gestation. The expression of PLAP was at firstconsidered to be onlyin the term placenta, though, a human PLAP-like variant has been found,thathas more than 85% homology with PLAP itself. PLAP is expressed strictly in normal term placenta, endocervix & fallopian tube and in ovarian and proximal gastrointestinal tumors. It is also widely expressed in germ cell tumors and more recently found in seminomas.

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.