Regulation of ceramide channels by Bcl-2 family proteins.

Mitochondrial outer membrane permeabilization to proteins, an irreversible step in apoptosis by which critical proteins are released, is tightly regulated by Bcl-2 family proteins. The exact nature of the release pathway is still undefined. Ceramide is an important sphingolipid, involved in various cellular processes including apoptosis. Here we describe the structural properties of ceramide channels and their regulation by the anti-apoptotic and pro-apoptotic proteins of the Bcl-2 family. The evolutionarily conserved regulation of ceramide channels by Bcl-2 family proteins, consistent with their role in apoptosis, lends credibility to the notion that ceramide channels constitute the protein release pathway.