Figure 7. PlyCB forms distinct membrane–protein complexes at high and low PS content of the bilayer.
CVO profiles (Heinrich and Lösche, 2014) of membrane-bound PlyCB on DOPC stBLMs containing (a) 15 mol% and (b,c) 30 mol% DOPS. Neutron reflection experiments were performed on neat bilayers and on bilayers in contact with protein-containing solutions, and co-refined (protein concentration in panels a and b: 5 μM and 600 nM, respectively). Panel (c) shows the same stBLM as in (b) after a buffer rinse to remove loosely associated protein from the membrane surface. Only the structures of the stBLMs in the presence of PlyCB protein are shown. The CVO profile in (a) shows accumulation of protein outside the bilayer, but no incorporation into the membrane. In distinction, the protein inserts deeply into the PS-rich bilayer, as indicated by the CVO profiles in panels b and c. The legend box in (c) applies to all panels. Confidence limits of the CVO profiles (not shown for the lipid components but indicated by dashed lines for the protein distributions) were determined by fitting the experimental data with a Monte Carlo Markov Chain.