Import of ADP/ATP carrier into mitochondria

We have identified the yeast homologue of Neurospora crassa MOM72,
the mitochondrial import receptor for the ADP/ATP carrier (AAC), by
functional studies and by cDNA sequencing. Mitochondria of a yeast
mutant in which the gene for MOM72 was disrupted were impaired in
specific binding and import of AAC. Unexpectedly, we found a
residual, yet significant import of AAC into mitochondria lacking
MOM72 that occurred via the receptor MOM19. We conclude that both
MOM72 and MOM19 can direct AAC into mitochondria, albeit with
different efficiency. Moreover, the precursor of MOM72 apparently
does not require a positively charged sequence at the extreme amino
terminus for targeting to mitochondria.