Figure 4.

Swelling of mitochondria blocks the assembly pathway of Tom40 but not of Tom22. Mitochondria isolated from wild-type yeast cells were preincubated in isotonic buffer or hypotonic (swelling) buffer for 30 min on ice. The mitochondria/mitoplasts were isolated and incubated with the ³⁵S-labeled precursors of Tom22 (A) and Tom40 (B) at 25°C for the indicated times. Mitochondria were reisolated, lysed in digitonin-containing buffer, and subjected to blue native electrophoresis and digital autoradiography. The asterisk indicates the low molecular weight form of the Tom22 assembly pathway.