Bcl-2 family proteins as ion-channels.

The Bcl-2 protein family function(s) as important regulators of cellular decisions to heed or ignore death signals. The three-dimensional structure of the Bcl-2 homolog, Bcl-XL, bears a strong resemblance to some pore-forming bacterial toxins. This similarity suggested that the Bcl-2 family proteins may also possess channel-forming capability. This review summarizes the recent initial studies on the in vitro channel activity of Bcl-2, Bcl-XL and Bax and offers some speculation as to the physiological role that these channels may play in the cell death pathway.