Bcl-2, Bcl-X L, and Bax are members of the Bcl-2 family that play important roles in apoptosis
regulation. These proteins are believed to be membrane-bound and to regulate apoptosis
through formation of homo-and heterodimers. However, we recently found by subcellular
fractionation that whereas Bcl-2 is predominantly a membrane protein as previously
reported, Bax and a significant fraction of Bcl-X L are soluble in thymocyte and splenocyte
extracts. In addition, we have demonstrated that the ability of Bax to form dimers appears to …