Skip to Content
Merck

Protein tyrosine phosphatase assays.

Current protocols in immunology (2011-04-05)
Ulrike Lorenz
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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Sodium molybdate, anhydrous, powder, −100 mesh particle size, 99.9% trace metals basis
Sigma-Aldrich
Sodium molybdate dihydrate, ≥99.5%, suitable for plant cell culture
Sigma-Aldrich
4-Nitrophenyl phosphate bis(tris) salt, for the determination of phosphatase, ≥97.0% (enzymatic)
Sigma-Aldrich
Sodium molybdate dihydrate, ≥99.5%
Sigma-Aldrich
Sodium molybdate, ≥98%
Sigma-Aldrich
Sodium molybdate dihydrate, 99.99% trace metals basis
Sigma-Aldrich
Sodium molybdate dihydrate, ACS reagent, ≥99%