Fig. 1: PTP1B dephosphorylates the JAK activation loops.
From: Structure guided studies of the interaction between PTP1B and JAK
a IL-6 dose response curves for phosphatases overexpressed in the M1 cell line. The effective concentration at which half the maximum response is observed (EC50) for the WT M1 cell line is approximately 2 ng/mL. Overexpression of PTP1B in the M1 cells caused a decrease in response to IL-6, with an EC50 of approximately 10 ng/mL. b Growth kinetics of WT M1 cells and PTP1B overexpressing M1 cells in the presence and absence of IL-6 as measured by incucyte. Data displayed are representative of 5 independent experiments. c Dephosphorylation assay of the four recombinant JAK kinase domains; JAK1, JAK2, JAK3 and TYK2 by PTP1B (-PTP1B denotes where no PTP1B was added to the reaction). (Top) Immunoblot (IB) probing for phosphorylated-JAK (P-JAK1 antibody) activation loop. (Bottom) Ponceau stained membrane to confirm equal input of proteins on gel. Data are representative of 3 independent experiments. d Overexpression of FLAG-JAK and HALO-PTP1B in HEK293T cells. Overexpression of PTP1B leads to a decrease in p-JAK1 when compared to cells not expressing PTP1B. Data displayed are representative of 3 independent experiments.
