Figure 2.

(A) Western blot analysis of N-19 and N-28 mutants expressed in COS-1 cells. Mitochondria-enriched fractions were prepared from COS-1 cells transfected with the indicated constructs expressing wild-type or mutant StAR proteins. (B and C) N-48 and N-62 StAR mutants are not imported into mitochondria or processed. Mitochondria-enriched subcellular fractions were prepared from COS-1 cells transfected with plasmids for wild-type StAR or the N-48 and N-62 mutants. One aliquot was incubated in buffer, the other in proteinase K; in some cases (C), an aliquot was incubated with 0.05% Triton X-100, before SDS/PAGE and Western blotting for StAR protein.