Synthetic radionuclides, such as the transuranic actinides plutonium, americium, and curium, present severe health threats as contaminants, and understanding the scope of the biochemical interactions involved in actinide uptake into cells is instrumental in managing human contamination. Recently, scientists have reported that an iron-binding protein called siderocalin can also bind and transport actinides into cells, a major advance in understanding the biological chemistry of radioactive metals. The research, which included X-ray crystallographic studies in the Berkeley Center for Structural Biology (Beamlines 5.0.1 and 5.0.2) at the Advanced Light Source (ALS), opens up new avenues of research into strategies for remedial action in the event of possible human exposure to nuclear contaminants. In addition, siderocalin, the protein studied, was selected as “Molecule of the Month” by the Protein Data Bank’s educational portal. Read more in the ALS Science Highlight.