FIGURE 4.

Tom20 is involved in endonucleolytic cleavage of the CBP1 mRNA. A, cleavage of the CBP1 mRNA is reduced in tom20Δ cells. W303xrn1Δ and W303tom20Δxrn1Δ cells harboring a control or wild-type TOM20 plasmid were analyzed by Northern blotting with probe B to detect the 3′ cleavage product, as described for Fig. 1D. B, cleavage of the MTS-GFP-ECIS-HIS3 reporter mRNA requires Tom20. RNA samples were analyzed by Northern blotting with a GFP probe (upper panel), and protein samples were analyzed by Western blotting with an anti-GFP antibody (lower panel). C, proposed model showing the mechanism by which the Sen complex controls the endonucleolytic cleavage of the CBP1 mRNA on the mitochondrial outer membrane. All of the results shown in the figure are representative of three independent experiments.