The bcl-2 protein is inserted into the outer membrane but not into the inner membrane of rat liver mitochondria in vitro.
The bcl-2 gene encodes a 26 kDa protein, overexpression of which blocks cell apoptosis. Since conflicting data have been reported concerning the localization of the Bcl-2 protein with mitochondrial inner and outer membranes, we analyzed in vitro import of the human Bcl-2 protein into isolated rat liver mitochondria. The Bcl-2 protein translated in rabbit reticulocyte lysate was efficiently inserted into the mitochondrial outer rather than the inner membrane in a membrane potential-independent manner. The carboxyl-terminal hydrophobic stretch is essential for the Bcl-2 protein to integrate into the outer membrane. Binding of the Bcl-2 protein to the mitochondria was not affected by pretreatment of the mitochondria with trypsin, indicating that the Bcl-2 protein does not require protease-sensitive mitochondrial surface components for its membrane insertion.
Nakai
M
M
Department of Chemistry, Faculty of Science, Nagoya University, Japan.
Takeda
A
A
Cleary
M L
ML
Endo
T
T
D000818:Animals; D001692:Biological Transport; D004252:DNA Mutational Analysis; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D008297:Male; D008930:Mitochondria, Liver / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D014176:Protein Biosynthesis; D011487:Protein Conformation; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2; D051381:Rats; D017208:Rats, Wistar; D013329:Structure-Activity Relationship; D014158:Transcription, Genetic; D014357:Trypsin / Q000378:metabolism
D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D014357:Trypsin