Bfk: A novel weakly proapoptotic member of the Bcl-2 protein family with a BH3 and a BH2 region

Abstract

Proteins of the Bcl-2 family are critical regulators of apoptosis. Proapoptotic members, like Bax, contain three of the four Bcl-2 homology regions (BH1-3), while BH3-only proteins, like Bim, possess only the short BH3 motif. Database searches revealed Bfk, an unusual novel member of the Bcl-2 family that contains a BH2 and BH3 region but not BH1 or BH4. Bfk is thus most closely related to Bcl-GL. It lacks a C-terminal membrane anchor and is cytosolic. Enforced expression of Bfk weakly promoted apoptosis and antagonized Bcl-2's prosurvival function. Like Bcl-GL, Bfk did not bind to any Bcl-2 family members, even though its BH3 motif can mediate association with prosurvival proteins. Low amou..