A HUMAN HOMOLOG OF THE MITOCHONDRIAL PROTEIN IMPORT RECEPTOR MOM19 CAN ASSEMBLE WITH THE YEAST MITOCHONDRIAL RECEPTOR COMPLEX

Import of preproteins into mitochondria requires transport machineries in both mitochondrial membranes that have been characterized in Sacch aromyces cerevisiae and Neurospora crassa By cDNA analysis, we identif ied a human protein of 16 kDa with significant overall homology to the fungal mitochondrial import receptor Mom19, including the three typic al characteristics: a hydrophobic N-terminal segment, a tetratrico pep tide motif in the middle and a negatively charged C-terminus, The huma n Mom19 homolog is expressed in all tissues analyzed. When synthesized in vitro, the human Mom19 homolog is targeted to isolated yeast mitoc hondria and specifically associates with the outer membrane receptor c omplex, suggesting that indeed a mitochondrial import receptor was ide ntified.