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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.

Serine/Threonine-protein phosphatase PP1-alpha catalytic subunit (PPP1CA) is crucial for cell division, and participates in the regulation of glycogen metabolism, muscle contractility and protein synthesis. The PPP1CA protein may have 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.

Acid Phosphatase-2, also known as ACP2 is composed of two subunits, Alpha & beta, and is chemically as well as genetically distinct from red cell acid phosphatase. ACP2 belongs to a family of distinct isoenzymes which hydrolyze orthophosphoric monoesters to alcohol and phosphate. In addition, Acid phosphatase deficiency is caused by mutations in the ACP2-beta subunit as well as ACP3-alpha subunit genes.

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.

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.

Protein Phosphatase 1F (PPM1F) is a part of the PP2C family of Ser/Thr protein phosphatases whose members are known to be negative regulators of cell stress response pathways. PPM1F interacts with Rho guanine nucleotide exchange factors (PIX), and as a result blocks the effects of p21-activated kinase 1 (PAK), a protein kinase mediating biological effects downstream of Rho GTPases. Calcium/calmodulin-dependent protein kinase II gamma (CAMK2G/CAMK-II) is one of the substrates of PPM1F. PPM1F is found to be an apoptosis Promoter.

Enolase-phosphatase E1 (ENOPH1) belongs to the MasA family of the HAD (halo-acid dehalogenase)-like hydrolase superfamily. ENOPH1 is a bifunctional enzyme which demonstrates both phosphatase and atypical enolase activities. ENOPH1 has a significant role in the ubiquitous methionine salvage pathway which is a biochemical pathway found in all organisms that regulate methionine levels in the cell.

Phosphoglycolate phosphatase (PGP) is discovered in all tissues including red cells, lymphocytes and cultured fibroblasts (at protein level). PGP is most active in skeletal muscle and cardiac muscle. The catalytic activity of PGP is 2-phosphoglycolate + H2O = glycolate + phosphate. Diseases associated with PGP include tardive dyskinesia and polycystic kidney disease.

DUSPs are distinguished by their ability to dephosphorylate both tyrosine and serine/threonine residues. DUSPs have been implicated as major modulators of critical signaling pathways. Dual specificity phosphatase 19 (DUSP19) belongs to the dual specificity protein phosphatase subfamily. DUSP19 is a protein phosphatase which functions as a stress-activated protein kinase pathway-regulating phosphatase. DUSP19 contains a variation of the consensus DUSP C-terminal catalytic domain, with the last serine residue replaced by alanine, and lacks the N-terminal CH2 domain found in the MKP class of DUSPs.

Phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) belongs to the HAD-like hydrolase superfamily. LHPP is an exceptional enzyme which hydrolyzes not only oxygen-phosphorus bonds in inorganic pyrophosphate but also nitrogen-phosphorus bonds in phospholysine, phosphohistidine and imidodiphosphate in vitro. LHPP is expressed in the liver, kidney and moderately in the brain.

PDXP is the active form of vitamin B6 that functions as a coenzyme in preserving biochemical homeostasis. The desired degradation route from PLP to 4-pyridoxic acid involves the dephosphorylation of PLP by PDXP. PDXP shows activity to pyridoxal 5''-phosphate (PLP), pyridoxine 5''-phosphate (PMP) and Pyridoxine 5''-phosphate (PNP), with a highest activity with PLP followed by PNP.

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).

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.

PPP3R2 is a calcium-dependent, calmodulin stimulated serine/threonine protein phosphatase. In eukaryotes, the phosphorylation and dephosphorylation of proteins on serine and threonine residues is a crucial means of regulating a wide range of cellular functions including division, homeostasis and apoptosis. Ordinarily the protein phosphatase (PP) holoenzyme is a trimeric complex composed of a regulatory subunit, a variable subunit and a catalytic subunit.

DUSP21 is a member of the protein-tyrosine phosphatase family. DUSPs inactivate their target kinases by dephosphorylating both the phosphoserine/threonine and phosphotyrosine residuesb. DUSP21 is able to dephosphorylate single and diphosphorylated synthetic MAPK peptides, favoring the phosphotyrosine and diphosphorylated forms over phosphothreonine. DUSP21 is only expressed in testis where there are dephosphorylated phosphotyrosine residues in MAPK peptides.

PPP1R14A is a phosphorylation-dependent inhibitor of smooth muscle myosin phosphatase. Inhibition of PPP1R14A results to increased myosin phosphorylation and enhances smooth muscle contraction in the absence of increased intracellular Ca(2+) concentration. Myosin phosphatase can reverse MYL (myosin light chain) phosphorylation to induce a state of relaxation. However, during agonist-induced contraction at constant Ca2+ concurrent inhibition of myosin phosphatase leads to increases in MYL phosphorylation and tension. These calcium-independent increases in myosin phosphorylation and tension are termed calcium sensitization.
Human pregnancy is characterized by the increases of PKN1 expression and CPI-17 phosphorylation in the myometrium. PPP1R14A is mapped to chromosome 19q13.13-q13.2.
PPP1R14A binds directly to protein kinase C and casein kinase I.
PPP1R14A siRNA decreased the level of merlin phosphorylation and consequently Ras and ERK activity in human tumor cell lines.
PKC/CPI-17 mediated pathway in histamine, triggeres cytoskeletal rearrangements causing lung microvascular barrier compromise.

Dual Specificity Phosphatase 26 (DUSP26) inhibits MAP kinase p38 by dephosphorylating it and inhibits p38-mediated apoptosis in anaplastic thyroid cancer cells. DUSP26 also induces activation of MAP kinase p38 and c-Jun N-terminal kinase. DUSP26 inactivates MAPK1 and MAPK3 which leads to dephosphorylation of heat shock factor protein 4 and a decrease in its DNA-binding activity.

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).

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.

Protein Phosphatase 1D (PPM1D) belongs to the PP2C family of Ser/Thr protein phosphatases whose members are negative regulators of cell stress response pathways. PPM1D is induced by tumor suppressor protein TP53/p53 in response to multiple environmental stresses. PPM1D is a negative regulator of the activity of p38 MAP kinase through which it reduces the phosphorylation of p53 and suppresses p53-mediated transcription and apoptosis. PPM1D is located in a chromosomal area which enlarges in breast cancer.

PPP1R1A is an inhibitor of protein-phosphatase 1. IPP-1 protein plays important in hormonal control of glycogen metabolism. Hormones that elevate intracellular cAMP elevate IPP-1 activity. PPP1R1A activation caused cAMP to control over proteins that are not directly phosphorylated by PKA following a rise in intracellular calcium, IPP-1 is inactivated by calcineurin (PP2B). Multiple domains in IPP-1 target cellular PP1 complexes. PPP1R1A is a cellular regulator of eIF2 alpha phosphorylation.

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.

Protein Phosphatase 2, Regulatory Subunit A Alpha, also known as PPP2R1A is part of the PPP family of phosphatases, which regulates a diversity of vital cellular processes. PPP2R1A subunit, PR65, functions as a scaffolding molecule which coordinates the assembly of the catalytic subunit and a variable regulatory B subunit. PPP2R1A is essential for proper chromosome segregation as well as for centromeric localization of SGOL1 in mitosis. Furthermore, PPP2R1A phosphorylation is an in vivo mechanism which regulates the PP2A signaling complex as well as increasing the PP2A activity in heart failure.