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PHPT1 is a member of the Janus protein familyand is 125 amino acid long. PHPT1 appears as a monomer in the cytoplasm and is an EDTA-insensitive phosphohistidine phosphatase. Overexpression of PHPT1 resolts in specific phosphohistidine phosphatase activity towards phosphopeptide I, with no activity detected towards phosphotyrosine, phosphothreonine and phosphoserine peptides.

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.

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.

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.

PPP3R1 is a Ser/Thr-specific calcium and calmodulin-dependent protein phosphatase which takes a vital part in the T cell activation pathway. Calcineurin is composed of two subunits; calcineurin A (CnA) and calcineurin B (CnB). Dephosphorylation of the nuclear factor of activated T-cells (NF-AT) by Calcineurin is essential for NF-AT activation, nuclear translocation, and early gene expression in T-cells.

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.

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.

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.

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.

Acid Phosphatase-5, also known as ACP5 is a member of the Purple acid phosphatase family. ACP5 is implicated in osteopontin as well as bone sialoprotein dephosphorylation. ACP5 expression appears to increase in certain pathological states for instance Gaucher & Hodgkin diseases, the hairy cell, the B-cell, as well as the T-cell leukemias.

Protein Phosphatase 1, Regulatory Subunit 8 (PPP1R8) is the RNA-binding subunit of a key species of protein phosphatase-1 in the nucleus. The PPP1R8 enzyme is an inhibitor subunit of the main nuclear protein phosphatase-1 (PP-1). PPP1R8 has RNA-binding activity however it doesn’t cleave RNA and may target PP-1 to RNA-associated substrates. Two isoforms of the PPP1R8 protein are specific inhibitors of type 1 serine/threonine protein phosphatases which can bind but not cleave RNA. The third isoform of the PPP1R8 protein is deficient in of the phosphatase inhibitory activity nonetheless it is a single-strand endoribonuclease comparable to RNase E of E. coli.

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.

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.

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.

Protein Phosphatase 4 Catalytic subunit (PPP4C), is a part of the Serine/threonine-protein phosphatase catalytic subunits which tskes part in dephosphorylation and regulation of HDAC3. The protein phosphatase (PP) holoenzyme is a trimeric complex compound of a regulatory subunit, a variable subunit and a catalytic subunit. 4 major families of protein phosphatase catalytic subunits have been identified, designated PP1, PP2A, PP2B (calcineurin) and PP2C.

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.

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.

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.

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.

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.

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.

Protein Phosphatase 1, Regulatory Subunit 2 (PPP1R2) is an inhibitor of protein-phosphatase 1 which forms heterodimer with PP1. PPP1R2 is a part of the protein phosphatase inhibitor 2 family.

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.