Role of membrane anchor domain of Bcl-2 in suppression of apoptosis caused by E1B-defective adenovirus.
Bcl-2 is an integral membrane protein that functions as a suppressor of programmed cell death. It contains a COOH-terminal signal anchor sequence that is selective for import and insertion of Bcl-2 into the mitochondrial outer membrane and, by a different mechanism, can also direct the protein to other membrane sites. Deletion of the signal anchor sequence rendered Bcl-2 cytosolic and impaired its ability to prevent apoptotic death of human KB cells infected with a mutant form of adenovirus type 5 that does not make E1B 19-kDa protein. When the predicted transmembrane domain of the Bcl-2 signal anchor was replaced with that of the signal anchor of the yeast outer mitochondrial membrane protein, Mas70p, the Bcl-2/Mas70p hybrid was found to be very similar to Bcl-2 in its distribution within transfected KB cells, in its ability to heterodimerize with Bax, and in its ability to suppress apoptosis. These results are consistent with a model in which the transmembrane segment contributes to the function of Bcl-2 by targeting and anchoring the protein to strategic membrane locations in the cell. Concentration of Bcl-2 at these sites may contribute to its proposed role as regulator, or component, of an antioxidant pathway.
Nguyen
M
M
Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
Branton
P E
PE
Walton
P A
PA
Oltvai
Z N
ZN
Korsmeyer
S J
SJ
Shore
G C
GC
D017501:Adenovirus E1B Proteins / Q000235:genetics*; D000260:Adenoviruses, Human / Q000235:genetics*; D000595:Amino Acid Sequence; D017209:Apoptosis / Q000502:physiology*; D001483:Base Sequence; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D007624:KB Cells; D007700:Kinetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009838:Oligodeoxyribonucleotides; D021382:Protein Sorting Signals / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2; D011519:Proto-Oncogenes; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014162:Transfection
D017501:Adenovirus E1B Proteins; D008565:Membrane Proteins; D009838:Oligodeoxyribonucleotides; D021382:Protein Sorting Signals; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D019204:GTP-Binding Proteins