title: Protein tyrosine phosphatase assays.
abstract: Tyrosine phosphorylation and dephosphorylation of proteins play a critical role in many processes of the immune system, from early development to fully differentiated effector function. Since the opposing actions of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs) determine the steady-state level of tyrosine phosphorylation on a given protein, it is often important for mechanistic studies to determine the specific activities of PTKs and PTPs. PTPs are defined by their enzymatic activity that catalyzes the dephosphorylation of phosphotyrosine residues. This unit focuses on methods to determine the enzymatic activity of PTPs. While there are many varieties of PTP assays, the focus in this unit is on immune complex PTP assays, which do not require elaborate biochemical purifications and are commonly used to test the activities of specific PTPs in the immune system.
authors.affiliation: The Beirne Carter Center for Immunology Research, Department of Microbiology, University of Virginia, Charlottesville, USA.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Lorenz
mesh_terms: D055162:Biocatalysis; D057075:Enzyme Assays / Q000379:methods*; D047468:Immunoprecipitation / Q000379:methods; D007553:Isotope Labeling / Q000379:methods; D008982:Molybdenum / Q000737:chemistry; D004676:Myelin Basic Protein / Q000378:metabolism; D009596:Nitrophenols / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D010710:Phosphates / Q000032:analysis / Q000737:chemistry; D010748:Phosphopeptides / Q000378:metabolism; D010761:Phosphorus Radioisotopes / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*; D012394:Rosaniline Dyes / Q000737:chemistry; D013053:Spectrophotometry
chemical_list: D004676:Myelin Basic Protein; D009596:Nitrophenols; D009943:Organophosphorus Compounds; D010710:Phosphates; D010748:Phosphopeptides; D010761:Phosphorus Radioisotopes; D012394:Rosaniline Dyes; C005095:malachite green; C008644:nitrophenylphosphate; D008982:Molybdenum; C024687:sodium molybdate(VI); D017027:Protein Tyrosine Phosphatases