Import of mutant tRNALys transcripts into isolated mitochondria. Autoradiographic detection of 5′-32P-labeled tRK1, tRK2, and in vitro transcripts after separation on a denaturing polyacrylamide gel. In vitro import assays, preparation of mitoplasts, and extraction of imported RNAs were as described (6) with modifications (9). Three pmoles of 32P-labeled RNA (tRNAs or transcripts) were used in each assay. Lanes: control, labeled tRK1 and tRK2, used as markers; imported RNAs, detection of RNase-protected RNAs extracted from mitoplasts after the import reaction; tr1, tr2, tr7, tr8, tr30, in vitro transcripts numbers (see Table 1). Asterisks indicate the positions of the nondegraded RNAs.