Produced in BL21 bacteria (Stratagene) using 0.5 mM IPTG induction. Bacterial pellets were lysed in NETN buffer (50 mM Tris-HCl pH8.0, 150 mM NaCl, 0.5 NP40, 5 mM EDTA, PIs), cleared by ultracentrifugation and bound to glutathione sepharose 4B (GE Healthcare) for 1 hr at 4 . Beads were washed with NETN, and amount of GST protein was estimated by SDS-PAGE followed by Coomassie staining. GST fusion