Lipid Bilayer Composition Affects Transmembrane Protein Orientation and Function

Figure 3

Mean phosphate (PO₄) detected (nmoL ± SE) in liposomes (lipid-only liposomes), Na⁺ K⁺-ATPase alone (enzyme-only), and proteoliposomes (liposomes containing ATPase) made by filtration (𝑛=3). Measurements were taken at 0, 10, 20, 30, 40, 50, 75, and 100 μl. Liposomes and proteoliposomes contained 0.5 μg lipid/μl prior to vesicle production, while proteoliposomes and enzyme-only contained 0.025 μg Na⁺ K⁺-ATPase/μl. The PO₄ in each well was detected by reading colour intensity at 750 nm. The slope across concentrations was linear with increasing concentration for enzyme-only and proteoliposomes (𝑃<.001).