Fig. 2.

Tom40 assembly into the outer membrane in mitochondria isolated from muscle of young and old animals. A: representative autoradiogram of Tom40 precursor protein import in mitochondria isolated from young and old animals for 0, 15, 30, and 60 min. Solubilized mitochondria were reisolated with digitonin and loaded on a 5–13% blue native (BN) gel. B and C: summary of multiple experiments (n = 7) illustrating the sequential import of Tom40 into intermediate I (I), intermediate II (II), and the translocases of the outer membrane (TOM) over 60 min, measured in both young (B) and old (C) animals. Values are expressed as a percentage change in the distribution of [³⁵S]hTom40 into each intermediate complex. *P < 0.05, effect of age on the final incorporation into the TOM complex at 60 min.