Fig. 2

Membrane docking states of SNX3. The electrostatic surface potential of the lipid-free structure is colored blue and red for positive and negative charges, respectively, as calculated with PROPKA settings at pH 7 and APBS⁵⁴, and oriented as in Fig. 1a in the top left. The PI3P binding pocket and affinity were shown by HSQC ligand titrations, with the SNX3 ribbon colored according to the extent of ¹H and ¹⁵N, CSPs by addition of 4.1 fold excess c₄-PI3P, as drawn in magenta (top, right). The site of nonspecific micelle association is shown by the surface of the PI3P-free PX domain (below, left) colored on the basis of absolute CSPs induced by addition of 160-fold excess DPC. The position of the lipid bilayer is shown in green. The site of stable micelle association by the PI3P-bound PX domain is shown by the ribbon structure at the lower right, which is colored according to the absolute CSPs induced by addition of c₄-PI3P to 20-fold DPC excess. The respective affinities based on the NMR titrations are indicated, and residues whose resonances show large, medium, small and no CSPs are colored red, orange, yellow, and white, respectively