Actin in action
A schematic illustration of Eric Sackmann's experiment. A portion of the giant vesicle is magnified to show the bilayer, which is made up of phospholipid molecules. Sackmann's group filled the vesicle with G-actin monomers (blue), some of which are labelled with a fluorescent dye (red), and saw uniform fluorescence when they imaged the giant artificial cell.
Next they injected magnesium ions into the cell to polymerize the G-actin to form filaments called F-actin. In this case they found that the fluorescence was concentrated in a thin layer just below the bilayer.