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A purified precursor polypeptide requires a cytosolic protein fraction for import into mitochondria.
Author(s) -
Ohta S.,
Schatz G.
Publication year - 1984
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1984.tb01862.x
Subject(s) - cytosol , mitochondrion , biology , protein subunit , cytoplasm , biochemistry , yeast , mitochondrial matrix , trypsin , microbiology and biotechnology , enzyme , gene
The beta‐subunit of mitochondrial ATPase is coded by a nuclear gene, synthesized outside the mitochondria as a larger precursor and imported into mitochondria. The beta‐subunit precursor was purified from yeast, both as a homogeneous, unlabeled polypeptide and in radiochemically pure form. Both precursor preparations were cleaved to the mature beta‐subunit by partially purified processing protease from the mitochondrial matrix. However, import of the radiochemically pure precursor into isolated yeast mitochondria required a cytosolic fraction from yeast or reticulocytes. The cytosolic factor was non‐dialyzable and trypsin‐sensitive; its apparent mol. wt. was approximately 40 000 as judged by gel filtration. Import of some proteins into mitochondria thus requires proteins of the ‘soluble’ cytoplasm.