Figure 6.

Weighted sum of squared residuals (χ²) produced from data collected before and after addition of protein to surface-deposited phospholipid bilayers. To test four possible protein positions in the bilayer [(i) inner headgroup region, (ii) inner acyl chain region, (iii) outer acyl chain region, and (iv) outer headgroup region], the solvent content of one layer at a time is decreased by 10% of the total volume at the same time as the SLD value of that same layer is increased to values corresponding to the presence of 10% protein. The χ² from the fit when positioning the protein in a layer is plotted constant throughout the layer as the SLD in the layer is assumed to be constant. The dashed lines are χ² values from applying the unperturbed bilayer models (Figure 4) on data collected after addition of protein (Figure 5).