Human and Dictyostelium SBDS are functional orthologs. (A) Schematic representation of the temperature-dependent intein splicing system to conditionally inactivate the Dictyostelium SBDS protein. (B) Temperature-dependent depletion of Dictyostelium SBDS protein in vivo. Spliced and unspliced SBDS proteins were detected by immunoblotting of wild type (WT) and sbdS^int(ts) cell extracts at the nonpermissive temperature (27°C). *Indicates nonspecific band used as loading control. (C) Plaque assays of sbdS^int(ts) cells transfected with empty vector control (pDM317) or plasmids expressing Dictyostelium SBDS or the indicated human SBDS-myc variants. Mean size of 10 plaques ± SEM at 7 days at 22°C is presented.