Rapid degradation of the presequence of the f1beta precursor of the ATP synthase inside mitochondria.

We have investigated the fate of the presequence of an overexpressed protein derived from the precursor of the F(1)beta subunit of ATP synthase after import and processing in mitochondria. Our studies revealed a rapid degradation of the presequence inside mitochondria catalysed by matrix-located protease(s). In contrast, the mature portion of the precursor was not degraded. This is the first experimental evidence of the rapid degradation of a mitochondrial presequence in organello after in vitro import and processing.