Protein sorting between mitochondrial membranes specified by position of the stop-transfer domain.
Recently, we fused a matrix-targeting signal to a large fragment of vesicular stomatitis virus G protein, which contains near its COOH-terminus a well-characterized endoplasmic reticulum (ER) stop-transfer sequence; the hybrid G protein was sorted to the inner mitochondrial membrane (Nguyen, M., and G. C. Shore. 1987. J. Biol. Chem. 262:3929-3931). Here, we show that the 19 amino acid G stop-transfer domain functions in an identical fashion when inserted toward the COOH-terminus of an otherwise normal matrix precursor protein, pre-ornithine carbamyl transferase; after import, the mutant protein was found anchored in the inner membrane via the stop-transfer sequence, with its NH2 terminus facing the matrix and its short COOH-terminal tail located in the intermembrane space. However, when the G stop-transfer sequence was placed near the NH2 terminus, the protein was inserted into the outer membrane, in the reverse orientation (NH2 terminus facing out, with a large COOH-terminal fragment located in the intermembrane space). These observations for mitochondrial topogenesis can be explained by a simple extension of existing models for ER sorting.
Nguyen
M
M
Department of Biochemistry, McGill University, Montreal, Canada.
Bell
A W
AW
Shore
G C
GC
D000595:Amino Acid Sequence; D000818:Animals; D004792:Enzyme Precursors / Q000378:metabolism; D007118:Immunoassay; D007425:Intracellular Membranes / Q000378:metabolism*; D008562:Membrane Glycoproteins; D008928:Mitochondria / Q000378:metabolism* / Q000648:ultrastructure; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D009954:Ornithine Carbamoyltransferase / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism; D014721:Vesicular stomatitis Indiana virus / Q000235:genetics / Q000378:metabolism*; D014759:Viral Envelope Proteins; D014763:Viral Matrix Proteins / Q000235:genetics / Q000378:metabolism*
D004792:Enzyme Precursors; C028391:G protein, vesicular stomatitis virus; D008562:Membrane Glycoproteins; D014759:Viral Envelope Proteins; D014763:Viral Matrix Proteins; D009954:Ornithine Carbamoyltransferase; D010447:Peptide Hydrolases