Selective localization of Bcl-2 to the inner mitochondrial and smooth endoplasmic reticulum membranes in mammalian cells.
Bcl-2, an anti-apoptotic protein, is believed to be localized in the outer mitochondrial membrane, endoplasmic reticulum, and nuclear envelope. However, Bcl-2 has also been suggested as playing a role in the maintenance of mitochondrial membrane potential, indicating its possible association with the inner mitochondrial membrane. We therefore further examined the exact localization of Bcl-2 in mitochondria purified from wild-type and bcl-2-transfected PC12 cells and pre- and postnatal rat brains. Double immunostaining demonstrated that Bcl-2 was co-localized with subunit beta of F1F0ATPase in the inner mitochondrial membrane. Biochemical analysis of isolated mitochondria using digitonin and trypsin suggests an association of Bcl-2 with the inner mitochondrial membrane. More interestingly, the majority of Bcl-2 disappeared from the inner membrane of mitochondria when cultured under serum deprivation. These results suggest that Bcl-2 acts as an anti-apoptotic regulator by localizing mainly to the inner mitochondrial and smooth ER membranes.
Gotow
T
T
Laboratory of Cell Biology, College of Nutrition, Koshien University, Hyogo, Japan.
Shibata
M
M
Kanamori
S
S
Tokuno
O
O
Ohsawa
Y
Y
Sato
N
N
Isahara
K
K
Yayoi
Y
Y
Watanabe
T
T
Leterrier
J F
JF
Linden
M
M
Kominami
E
E
Uchiyama
Y
Y
D000818:Animals; D016895:Culture Media, Serum-Free; D004072:Digitonin / Q000494:pharmacology; D018871:Endoplasmic Reticulum, Smooth / Q000737:chemistry* / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry; D007425:Intracellular Membranes / Q000737:chemistry* / Q000648:ultrastructure*; D051379:Mice; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000737:chemistry* / Q000187:drug effects / Q000648:ultrastructure; D009474:Neurons / Q000737:chemistry* / Q000648:ultrastructure; D016716:PC12 Cells; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis* / Q000276:immunology; D006180:Proton-Translocating ATPases / Q000032:analysis / Q000276:immunology; D051381:Rats; D011994:Recombinant Proteins; D013347:Subcellular Fractions; D014162:Transfection
D016895:Culture Media, Serum-Free; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins; D006180:Proton-Translocating ATPases; D004072:Digitonin