Direct evidence for membrane pore formation by the apoptotic protein Bax.
Direct imaging of the interaction of the apoptotic protein, Bax, with membrane bilayers shows the presence of toroidal-shaped pores using atomic force microscopy. These pores are sufficiently large to allow passage of proteins from the intermitochondrial space. Both the perturbation of the membrane and the amount of protein bound to the bilayer are increased in the presence of calcium. The results from the imaging are consistent with leakage studies from liposomes of the same composition. The work shows that Bax by itself can form pores in membrane bilayers.
Epand
Raquel F
RF
Department of Biochemistry, McMaster University Health Sciences Centre, Hamilton, Ont., Canada. epand@mcmaster.ca
Martinou
Jean-Claude
JC
Montessuit
Sylvie
S
Epand
Richard M
RM
Yip
Christopher M
CM
D017209:Apoptosis / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D066298:In Vitro Techniques; D008051:Lipid Bilayers; D008081:Liposomes; D008566:Membranes / Q000378:metabolism / Q000648:ultrastructure; D018625:Microscopy, Atomic Force; D008928:Mitochondria / Q000378:metabolism / Q000648:ultrastructure; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein
D008051:Lipid Bilayers; D008081:Liposomes; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D002118:Calcium