Figure 6.

Membrane interaction of GDP- and GppNHp-loaded Arl2/3 in complex with UNC119a. (A) SPR sensorgrams of the binding of UNC119a-complexed Arl2/3 (c_Arl2/3 = 2 μM, c_UNC119a = 3 μM), as well as UNC119a alone, to anionic model raft membranes composed of DOPC/DOPG/DPPC/DPPG/Chol 20:5:45:5:25 (mol %). Side-by-side comparisons of the SPR curves are shown in Fig. S5. (B) Corresponding SPR data for the initial association process. The error bars represent the standard deviation from three to nine measurements. (C) Surface pressure/time isotherms for the membrane interaction of Arl2/3 in complex with UNC119a (2:3 molar ratio), as well as UNC119a alone, with anionic lipid raft monolayers. (D–F) Corresponding time-dependent IRRA spectra for the amide-I′ region of Arl3•GppNHp (D), Arl2•GDP (E), and Arl2•GppNHp (F) in complex with UNC119a in the presence of anionic lipid raft monolayers. All IRRA spectra were recorded with p-polarized light at a 35° angle of incidence. To see this figure in color, go online.