An application that appears particularly promising is to use APols as a mild, stabilizing medium in which to fold membrane proteins (Pocanschi et al. (2006), Dahmane et al. (2011), Bazzacco et al. (2012)), including G protein-coupled receptors (Dahmane et al. (2009), Bazzacco et al. (2012),Banères et al. (2011)). The folding yields achieved for the latter are much higher than those observed in detergent or lipid/detergent solutions (Fig. 7). GPCRs folded in APols can then be, if need be, purified to near-homogeneity by affinity chromatography (Dahmane et al. (2009), Banères et al. (2011)).
Another promising application is to use functionalized APols for immobilizing MPs onto solid supports (Charvolin et al. (2009), Pocanschi et al. (2006), Popot et al. (1987)). As long as APols are not displaced by another surfactant, their association with MPs, albeit non-covalent, is irreversible, and resists extensive washing with surfactant-free buffer (Popot et al. (2003),Tribet et al. (2009),Zoonens et al. (2007), Charvolin et al. (2009), Tribet et al. (1997)). Trapping a MP with a functionalized APol therefore results in a permanently functionalized complex (Zoonens et al. (2007)). This has innumerable possible applications. In particular, appropriately tagged APols can be used to immobilize the MPs they associate with onto solid supports in a simple, mild and versatile manner. The ligand-binding properties of the immobilized proteins can then be studied, in detergent-free solutions, by any convenient observation method, opening the way to a host of applications in diagnostics, drug discovery, or the search for natural biological partners ( Charvolin et al. (2009)) (Fig. 8).