Protein A conjugated 10 nm gold nanoparticles (Insight Biotechnology) were used to act as fiducial markers when processing the tomograms. The markers were added following LUV formation. First the Protein A 10nm gold solution was concentrated using a centrifuge (XG, 30 minutes) and resuspended in a solution of 40 mM HEPES and 20 mM sodium chloride buffered to pH 7.4. 10 µL of suspended protein A was added to 10 µL of LUV sample. Copper Quantifoil grids (400 mesh, 2/2) were glow discharged for 33 seconds at 10 mA using a Cressington208 carbon coater. 3 µL of the samples were then placed directly on the grid which was blotted and vitrified using a FEI Vitrobot mk IV using a blot time of 6 seconds and a blot force of 6 at 4 °C and 100% relative humidity. The samples were kept under liquid nitrogen until required.