Fig. 4. Mitochondrial uptake of DNA is an active process. (A) DNA uptake requires the ΔΨ potential. Mitochondrial incorporation of labeled maize 2.3 kb plasmid was tested in the presence of a constant concentration of succinate and increasing concentrations of malonate. (B) DNA uptake requires the proton motive force. Mitochondrial incorporation of labeled maize 2.3 kb plasmid was tested in the presence of increasing concentrations of the protonophore CCCP. (C and D) DNA uptake is inhibited by KCl and MgCl₂. Mitochondrial incorporation of labeled maize 2.3 kb plasmid was tested in the presence of increasing concentrations of KCl (C) or MgCl₂ (D). Migration of the incorporated plasmid (2.3PL) is indicated.