Figure 1.

Biotin-containing proteins are present in the T. gondii apicoplast and mitochondrion. Incubation of fixed parasites with FITC-conjugated streptavidin detects a biotin-dependent protein in the apicoplast (A), as indicated by colocalization with ACP. ACP was shown previously to be localized in the apicoplast (5). Overexposure of streptavidin-FITC-labeled parasites indicates the presence of another biotin-containing protein, presumably pyruvate carboxylase, in the mitochondria (arrows), as confirmed by colocalization with the mitochondrial-specific marker Mitotracker Red (not shown) (B).