INACTIVATION OF BCL-2 BY PHOSPHORYLATION

The antiapoptosis potential of Bcl-2 protein is well established, but the mechanism of Bcl-2 action is still poorly understood. Using the ph osphatase inhibitor okadaic acid or the chemotherapeutic drug taxol, w e found that Bcl-2 was phosphorylated in lymphoid cells. Phospho amino acid analysis revealed that Bcl-2 was phosphorylated on serine. Under similar conditions, okadaic acid or taxol treatment led to the induct ion of apoptosis in these cells. Thus, phosphorylation of Bcl-2 seems to inhibit its ability to interfere with apoptosis. In addition, phosp horylated Bcl-2 can no longer prevent lipid peroxidation as required t o protect cells from apoptosis.