Open AccessImported mitochondrial proteins cytochrome b2 and cytochrome c1 are processed in two steps.
Author(s) -
Susan M. Gasser,
Akiyoshi Ohashi,
Günther Daum,
Peter Böhni,
Jane Gibson,
Graeme A. Reid,
Takashi Yonetani,
Gottfried Schatz
Publication year - 1982
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.79.2.267
Subject(s) - cytochrome , inner mitochondrial membrane , cytochrome c , translocase of the inner membrane , cytochrome c1 , inner membrane , mitochondrion , biochemistry , cytochrome b , bacterial outer membrane , heme , mitochondrial matrix , membrane , hemeprotein , chemistry , coenzyme q – cytochrome c reductase , biology , mitochondrial membrane transport protein , mitochondrial dna , cytosol , enzyme , escherichia coli , gene
Cytochrome b2 of yeast is located in the space between the inner and outer mitochondrial membranes whereas cytochrome c1 is bound to the outer face of the mitochondrial inner membrane. Both proteins are made outside the mitochondria as larger precursors that are processed to their mature forms in two steps. In the first step, at least a segment of the precursor polypeptide chain penetrates into the mitochondrial matrix and is cleaved to an intermediate form by a matrix-localized soluble protease. This step requires an electrochemical gradient across the mitochondrial inner membrane. In the second step, the intermediate form is converted to the mature form. For cytochrome c1, this second step requires heme. Import of these two cytochromes thus involves a "detour" across the inner membrane.