Origin, targeting, and function of the apicomplexan plastid

The discovery of a plastid in Plasmodium, Toxoplasma and related protozoan parasites provides a satisfying resolution to several long-standing mysteri es: the mechanism of action for Various surprisingly effective antibiotics; the subcellular location of an enigmatic 35 kb episomal DNA; and the natur e of an unusual intracellular structure containing multiple membranes. The apicomplexan plastid highlights the importance of lateral genetic transfer in evolution and provides an accessible system for the investigation of pro tein targeting to secondary endosymbiotic organelles. Combining molecular g enetic identification of targeting signals with whole genome analysis promi ses to yield a complete picture of organellar metabolic pathways and new ta rgets for drug design.