Tyrosine Phosphatase Assay Kits

• Cdc25
• Cdi/KAP
• LMW-PTP/ACP1
• PTP1B
• TC-PTP
• DUSP1/MKP-1

Protein Phosphatase Cdc25A, B, C Fluorometric Assay Kit

CycLex Protein Phosphatase Cdc25A, B, and C Fluorometric Assay Kit is a fluorometric and non-radioactive assay designed to measure the activity of Cdc25A, B, and C protein phosphatase.

Activation of cyclin-dependent kinases in higher eukaryotic cells can be achieved through dephosphorylation of two conserved residues, Thr14 and Tyr15, by members of the Cdc25 phosphatase family, Cdc25A, Cdc25B and Cdc25C. The Cdc25 dual-specificity phosphatases control progression through the eukaryotic cell division cycle by activating cyclin-dependent kinases. Cdc25A plays an important role at the G1/S-phase transition. Cdc25A degradation during mitotic exit and in early G1 is mediated by the anaphase-promoting complex (APC/C) or cyclosome (Cdh1) ligase, and a KEN-box motif in the N-terminus of the protein is required for its targeted degradation. Cdc25B undergoes activation during S-phase and plays a role in activating the mitotic kinase Cdk1/cyclin B in the cytoplasm. Active Cdk1/cyclin B then phosphorylates and activates Cdc25C leading to a positive feedback mechanism and to entry into mitosis. In addition to their essential function in the normal cell cycle, cdc25 phosphatases are involved in the checkpoint-induced control of cell cycle progression. Finally, Cdc25A and B phosphatases have been shown to possess an important oncogenic potential and to be overexpressed in a variety of cancers and cancer cell lines.

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Protein Phosphatase Cdi/KAP Fluorometric Assay Kit

CycLex Cdi1 / KAP Fluorometric Assay Kit is a fluorometric and non-radioactive assay designed to measure the activity of Cdi1/KAP protein phosphatase.

A Cdk-interacting protein called Cdi1 (cyclin-dependent kinase interactor 1)/KAP (kinase associated phosphatase) was first identified as a novel G1- and S-phase dual-specificity phosphatase that associates with Cdk2 and/or Cdc2 by the interaction trap, a yeast genetic selection for interacting proteins. Phosphatases have also been shown to play an important role in regulating a variety of signal transduction pathways that have a bearing on cancer. It was reported that the Cdi1/KAP gene is overexpressed in human breast and prostate cancer using differential screening and that breast and prostate malignancies are associated with high levels of KAP expression.

Protein Phosphatase LMW-PTP/ACP1 Fluorometric Assay Kit

CycLex Protein Phosphatase LMW-PTP/ACP1 Fluorometric Assay Kit is a fluorometric and non-radioactive assay designed to measure the activity of LMW-PTP/ACP1 protein phosphatase.

The low molecular weight protein tyrosine phosphatase (LMW-PTP) is an 18-kDa cytosolic enzyme, also known as acidic protein phosphatase 1 (ACP1). LMW-PTP/ACP1 is specific for phosphotyrosine in peptides and proteins, but the enzyme shares very limited sequence homology with other PTPases. Recent studies suggested that entopic overexpression of LMW-PTP/ACP1 is sufficient to confer transformation in epithelial cells and that LMW-PTP/ACP1’s oncogenic activities required EphA2. LMW-PTP/ACP1 negatively regulates EphA2 receptor tyrosine kinase. LMW-PTP/ACP1 is a positive regulator of both tumor onset and development through ephrin- EphA2 signaling process, and it is a potential target of anticancer drug development.

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Protein Tyrosine Phosphatase 1B (PTP1B) Fluorometric assay Kit

CycLex PTP1B Fluorometric Assay Kit is a fluorometric and nonradioactive assay designed to measure the activity of protein tyrosine phosphatase, especially Protein Tyrosine Phosphatase 1B (PTP1B).

The protein-tyrosine phosphatase PTP1B, a ubiquitous, non-transmembrane protein tyrosine phosphatase, is responsible for negatively regulating insulin signaling by dephosphorylating the phosphotyrosine residues of the insulin receptor kinase. On a high-fat diet, PTP1B-deficient mice were resistant to weight gain and remained insulin sensitive, while wild type mice rapidly gained weight and became insulin resistant. These results suggested a major role for PTP1B in modulation of insulin sensitivity and fuel metabolism, possibly involving PTP1B regulation of the leptin receptor pathway. Therefore, it has been proposed that PTP1B is a potential therapeutic target for the treatment of type II diabetes and obesity.

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T-cell Protein Tyrosine Phosphatase (TC-PTP) Fluorometric Assay Kit

CycLex TC-PTP Fluorometric Assay Kit is a fluorometric and nonradioactive assay designed to measure the activity of protein tyrosine phosphatase, especially T-cell tyrosine phosphatase (TC-PTP/PTPN2).

The human T-cell PTP (TC-PTP) is an intracellular non-transmembrane phosphatase that was originally cloned from a T-cell cDNA library, but is now known to be expressed in many tissues. TC-PTP has been implicated in the regulation of growth factor receptor signaling, both at the level of receptor tyrosine phosphorylation and in the regulation of downstream signaling events. The overexpression of a truncated, active form of TC-PTP has been shown to reduce the tyrosine phosphorylation of several proteins in PDGF-stimulated cells. In addition, TC-PTP has been linked to the dephosphorylation of the insulin receptor and acts as a negative regulator of cytokine signaling through dephosphorylation of the Jak family of tyrosine kinases.

Protein Phosphatase DUSP1/MKP-1 Fluorometric Assay Kit

CycLex DUSP1/MKP-1 Fluorometric Assay Kit is a fluorometric and nonradioactive assay designed to measure the activity of DUSP1/MKP-1 protein phosphatase.

DUSP1 is a member of a family of dual-specificity phosphatases that dephosphorylate both phosphothreonine and phosphotyrosine residues and contain a highly conserved C-terminal catalytic domain and an N-terminal Cdc25-like (CH2) domain. DUSP1 is also known as MKP-1 (mitogen-activated protein (MAP) kinase phosphatase-1) and inactivates MAP kinase by the concomitant dephosphorylation of both its phosphothreonine and phosphotyrosine residues. The expression of DUSP1/MKP-1 is induced in human skin fibroblasts by oxidative/heat stress and growth factors. DUSP1/MKP-1 may play an important role in the human cellular response to environmental stress as well as in the negative regulation of cellular proliferation via the dephosphorylation of MAP kinase. A recent study also shows that DUSP1/MKP-1 is a key factor of major depressive disorder (MDD) and it may be a new drug target for treating depression and possibly other mood disorders.

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