Figure 3. Frizzled 7 peptide enhances the interaction of syntenin PDZ2 with PIP₂-containing composite liposomes.

Sensorgrams illustrating the binding of increasing concentrations of PDZ2 wild-type (a,b) or PDZ2 mutant K214A/K250A (c,d) to liposomes containing 30% PC/40% PE/20% PS and either 10% PI (black line) or 5% PI and 5% PIP₂ (grey line) in the absence (a,c) or in the presence (b,d) of 2 mM of KGETAV Frizzled 7 peptide. (e) Signals obtained at equilibrium using 5% PIP₂-containing liposomes and PDZ2 wild type in the absence (black continuous line) or in the presence of 2 mM of Frizzled 7 peptides (KGETAV, grey continuous line; AGETAV, black dotted line; EGETAV, grey dotted line) were subtracted for association to 10% PI liposomes and plotted as a function of protein concentration. Note that solely the wild-type peptide (KGETAV) enhances PDZ2 interaction with PIP₂ embedded in liposomes. The data show one experiment representative of three independent experiments done in duplicate. RU, response units. Supplementary Fig. 3 illustrates that the enhancement of PDZ2 interaction with PIP₂ embedded in liposomes in the presence of Frizzled 7 peptide is lost when the PDZ2 carries K214A, K250A or N215D mutations. It also illustrates that PDZ1 in isolation strongly interacts with liposomes, but not with PIP₂ embedded in liposomes, even in the presence of Frizzled 7 peptide.