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Protein tyrosine phosphatases: their roles in signal transduction
1Department of Biological Chemistry, University of Michigan, Ann Arbor 48109-0606, USA.
Abstract:
Protein tyrosine phosphatases play critical roles in a number of cellular signal transduction pathways. Receptor-like PTPases such as CD45 are essential for antigen-induced proliferative responses of T-cells. Intracellular PTPases have been shown to associate with specific growth factor receptors and this association has a dramatic effect on receptor signaling mechanisms. Other phosphatases (e.g., the product of the CDC25 gene) are essential for cell cycle progression. It appears that the cellular location of the intracellular PTPases plays an important role in defining the substrate specificity. Phosphatases are also present in both pathogenic bacteria and viruses. These PTPases most likely function to disrupt important signal transduction pathways present in the host. More than 30 different phosphatases have been cloned and characterized. A detailed understanding of their catalytic properties suggests that all PTPases use a common mechanism for removing phosphatase from various phosphoproteins. Two PTPase structures recently have been determined. The structural information along with biochemical and kinetic data provides a basis for understanding the catalytic properties of these enzymes.
Insights
Protein tyrosine phosphatases (PTPases) are vital enzymes in cell signaling, regulating processes from T-cell responses to cell cycle progression. Their diverse roles and common catalytic mechanisms are being elucidated through structural and biochemical studies.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Protein tyrosine phosphatases (PTPases) are crucial enzymes involved in cellular signal transduction.
- Specific PTPases, like CD45, regulate T-cell activation, while others, such as CDC25, are essential for cell cycle control.
- PTPases are also found in pathogens, potentially disrupting host signaling.
Purpose of the Study:
- To explore the diverse roles of PTPases in cellular processes and their presence in pathogenic organisms.
- To understand the common catalytic mechanisms employed by PTPases.
- To leverage structural and biochemical data for a comprehensive understanding of PTPase function.
Main Methods:
- Literature review and characterization of over 30 cloned PTPases.
- Biochemical and kinetic analysis of PTPase activity.
- Determination of PTPase enzyme structures.
Main Results:
- PTPases regulate critical cellular pathways including T-cell proliferation and cell cycle progression.
- Substrate specificity is influenced by the cellular localization of intracellular PTPases.
- All characterized PTPases appear to utilize a conserved catalytic mechanism.
- Structural data for two PTPases have been determined.
Conclusions:
- PTPases are essential enzymes with diverse roles in eukaryotic cells and pathogens.
- A common catalytic mechanism underlies PTPase function.
- Structural and biochemical insights are key to understanding PTPase catalytic properties and their biological significance.