Figure 5.

Accumulation of the precursor form of a cleavable mitochondrial protein in the mitochondrial outer membrane. (A) Two presequence peptides of cytochrome b₂ identified from the 2D-BAC/SDS-PAGE of purified outer membranes vesicles (Figure 2). Numbers indicate amino acid residues. The processing of cytochrome b₂ occurs in two steps, after residue 31 and after residue 80. (B) The precursor form of F₁β migrates in the outer membrane fraction. Outer and inner membrane vesicles from wild-type yeast mitochondria were separated on a sucrose gradient, and fractions were analyzed by SDS-PAGE and Western blotting. Immunoreactive bands were quantified and the maximal value was set to 100% for each protein. p-F₁β, precursor form; m-F₁β, mature protein.