The N‐terminal 21 amino acids of a 70 kDa protein of the yeast mitochondrial outer membrane direct E. coli β‐galactosidase into the mitochondrial matrix space in yeast cells

The intracellular location of fusion proteins was investigated in yeast cells. They consisted of the N-terminal 21, 61 or 292 amino acids of the 70 kDa protein of the yeast mitochondrial outer membrane and an enzymatically active E. coli beta-galactosidase. The hybrids containing 61 or 292 residues of the 70 kDa protein, as well as the original 70 kDa protein, were localized on the outer membrane in a tightly membrane-bound form. In contrast, the other hybrid was exclusively localized in the mitochondrial matrix space as a soluble protein.