Fig. 3. Subcellular fractionation of COS-7 cells expressing the various GFP constructs. Transfected COS-7 were lysed and after clarification of the cellular debris by centrifugation were fractionated into supernatant (S) and pellet (P) fractions by ultracentrifugation for 16 hours at 200,000 g as described in the Materials and Methods. The fractions were subjected to SDS-PAGE, analyzed by western blot with an antibody against GFP, and the resulting bands were quantified using UVIband V97 software. These results are representative of a minimum of five independent fractionations, with less than 5% variation among different experiments.