Figure 6.

Competition assay performed in nanoliter droplets. (A) Schematic representation of the competition assay in nanoliter plugs. Both the receptor HumRadA18 and the labeled ligand BRC4^fl were kept at constant concentration during the whole titration while the MBP-BRC4 concentration is increasing from 0 to 7 μM. (B) Competition of MBP-BRC4 construct with BRC4^fl against HumRadA18. Binding curves were normalized to % of bound HumRadA18-BRC4^fl. Two identical repeat titrations are overlaid. The well contained initially 40 μL of 40 nM BRC4^fl and 60 nM HumRadA18 in CHES buffer pH 9.5, 1% BSA (w/v). The injection of purified MBP-BRC4 was done at a flow rate of 2.5 μL/min (for 1 min) followed by 17.5 μL/min (for 1 min). Vertical error bars correspond to the standard deviation of the mean anisotropy for each droplet.