Transmission electron micrograph of spectrin in cell fractionation. Dr. V. T. Marchesi and colleagues took advantage of the high purity of red cell ghosts obtained by hypotonic lysis to analyze the properties of membrane proteins. They identified spectrin as a major red cell membrane cytoskeletal protein responsible for maintaining the biconcave shape of red cells. Image made available by James D. Jamieson and the Department of Cell Biology, Yale University School of Medicine.