Metabolic labeling of O. tauri and D. discoideum with 75Se. O. tauri and D. discoideum cells were grown in the presence of 75Se [selenite], cell lysates prepared, proteins resolved by SDS-PAGE and analyzed using a PhosphorImager. (a) O. tauri. Three middle lanes represent the soluble fraction, homogenate and pellet fraction as shown above the gel. For comparison, HEK 293 cells were metabolically labeled with 75Se, and migrations of thioredoxin reductase 1 (TR1) and glutathione peroxidase 1 (GPx1) are shown. (b) D. discoideum. Two middle lanes represent two independent samples of 75Se-labeled D. discoideum cells. The four radioactive bands correspond to the indicated selenoproteins identified in silico. For comparison, monkey CV-1 cells were metabolically labeled with 75Se, and migrations of TR1 and GPx1 are shown on the right.