Figure 4.

In vitro kinase activity of TYK2 WT, TYK2 S431G, and TYK2 R832W proteins. TYK2 was immunoprecipitated with anti-TYK2 Ab from non-stimulated cells or cells stimulated with IFNα (500 pM) for 15 min and subjected to in vitro kinase reaction in the presence or absence of 30 μM ATP for 5 min at 30 °C. Recombinant STAT3 (rSTAT3) was added to the reaction as exogenous substrate. The phosphorylation level of the indicated proteins was analysed by immunoblotting. STAT3 phosphorylation was represented relative to rSTAT3 and then to TYK2, to account for differences in the amount of immunoprecipitated TYK2 in each sample. Values are expressed as percentage of the highest value of each membrane. A representative result of three independent experiments is shown.