| Abstract: | The thickness of the red cell membrane skeleton was deduced from measurements of the isthmus zones of intact cells that were maximally narrowed by one of two independent methods. The first method involved application of viscous drag to red cells entrapped between spider web fibers. The second method utilized cellular dehydration followed by spectrin denaturation at 49.5 degrees C. Measurements on thin sections showed that the isthmus is narrowed to approximately 120 nm by either method, suggesting that the membrane skeleton occupies a zone beneath the lipid bilayer that is up to 60 nm in thickness. The tertiary and quarternary structure of band 3, a major integral membrane protein that anchors the membrane skeleton to the lipid bilayers may be a critical determinant of the location of the membrane skeleton within the red cell. |
