Targeting of the master receptor MOM19 to mitochondria

The targeting of proteins to mitochondria involves the recognition
of the precursor proteins by receptors on the mitochondrial surface
followed by insertion of the precursors into the outer membrane at
the general insertion site GIP. Most mitochondrial proteins
analyzed so far use a mitochondrial outer membrane protein of 19
kilodaltons (MOM19) as an import receptor. The gene encoding MOM19
has now been isolated. The deduced amino acid sequence predicts
that MOM19 is anchored in the outer membrane by an NH2-terminal
hydrophobic sequence, while the rest of the protein forms a
hydrophilic domain exposed to the cytosol. MOM19 was targeted to
the mitochondria via a pathway that is independent of
protease-accessible surface receptors and controlled by direct
assembly of the MOM19 precursor with GIP.