The polymeric state of actin in the human erythrocyte cytoskeleton

Reports on the polymeric state of actin in the red cell have been diverse. We have used phalloidin to stabilize the actin in erythrocyte ghosts prior to extraction in low ionic strength media. A mild proteolytic digestion and Sepharose 4B gel filtration enable an F-actin polymer to be isolated in pure form [1]. Detailed size analysis of this polymer in a range of experiments suggests that actin exists in the erythrocyte principally as a polymer of 100 nm length composed of 30 monomers in a double helical chain 15 monomers long with an estimated molecular weight of 1.3 X 10(6) daltons.