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Figure 2 KCNH2 (HERG) Channel Currents and Western Blot Analysis of Autoantibodies Produced Against KCNH2
(A) Representative KCNH2 (HERG) channel currents recorded from HEK 293 cells cultured in control medium (left) and medium supplemented with 2% serum from the patient (right). (B) Representative KCNH2 channel currents recorded from HEK 293 cells cultured in control medium (left) and medium supplemented with 75 µg/ml immunoglobulin (Ig)G from the patient (right). (C) Current (I)–voltage relationships of Istep (left) and Itail (right) recorded from HEK 293 cells cultured in control medium (open circles; n = 4) or a medium supplemented with either 7.5 µg/ml (solid circles; n = 7) or 75 µg/ml (solid squares; n = 7) IgG. The lines fitted to Itail data (right) represent Boltzmann functions. (D) A comparison of the dose-dependent effects of serum (0.2% and 2%) and IgG (7.5 and 75 µg/ml) added to the culture medium (control) of HEK 293 cells expressing KCNH2 on maximal Itail amplitude. (E) Western blot analysis of autoantibodies produced against KCNH2. Lane 1: IgG from a healthy control subject; lane 2: IgG from the patient; lane 3: pre-incubation of the HEK 293 lysate expressing KCNH2 protein with IgG from the patient; lane 4: anti-KCNH2 polyclonal antibodies (positive control).