Figure 3.

α Complementation. (A) Yeast cultures harboring ωc and the indicated plasmids were streaked on galactose medium plates containing X-gal. Blue colonies detect α fragments that are in the cytosol and associate with cytosolic ω (ωc); Aco1-α fusion protein, cytochrome b₂-α (fully imported into mitochondria), FumΔSP-α (lacking a mitochondrial targeting signal and localized only in the cytosol), αc (cytosolic α fragment). (B) β-Galactosidase activity. Yeast cultures harboring the indicated plasmids were grown in galactose medium, and culture extracts were assayed for β galactosidase activity.