Figure 4.

CL promotes processing of the Yfh1 precursor. Mitochondria (Mito.) were isolated from WT and crd1Δ cells and incubated with ³⁵S-labeled precursors Yfh1 (top panel of A), or ³⁵S-labeled Isu1, Yah1, or Nfs1 (B) in the presence or absence of a membrane potential (Δψ). Following import, the samples were treated with proteinase K, which removes portions of the nonimported precursor proteins. The import reactions were analyzed by SDS-PAGE and autoradiography. A, lower panels, quantification of the intermediate and mature forms of Yfh1 in four independent import experiments with the corresponding standard error of the mean. As control, the longest import time point of Yfh1 into WT mitochondria was set to 100%. C, the membrane potential of WT and crd1Δ mitochondria was measured by quenching of the fluorescence of DiSC₃. The reaction was stopped by addition of the AVO mix.