Import of Cytochrome c1 and Cytochrome b2 into Mitochondria
We have investigated the import pathways of the two mitochondrial proteins, cytochrome c1 (Neurospora crassa) and b2 (yeast). These proteins are synthesized in the cytosol as larger precursor molecules, posttranslationally imported into mitochondria and processed in two steps to their respective mature sized forms (1). Cytochrome c1 is a protein of the inner mitochondrial membrane with a large hydrophilic domain exposed to the intermembrane space. Cytochrome b2 is a soluble protein of the intermembrane space. Both proteins enter mitochondria via translocation contact sites (2).