Discusses how metals are routed and incorporated into regulatory and catalytic proteins and how their pathways are regulated. Describes the diverse strategies that organisms have adopted to acquire, utilize, and store essential metals while protecting themselves against metal toxicity. Metal ion homeostasis and detoxification are considered in terms of structure and regulation. Covers the role of metals in DNA-binding proteins and gene regulation, the chemistry and biology of metal-binding peptides, and methods of metal detoxification. Also includes structural and functional studies of metalloproteins, and a section on the physiology and diseases of unbalanced metal ion homeostasis.