LOCALIZATION OF THE BCL-2 PROTEIN TO THE OUTER MITOCHONDRIAL-MEMBRANEBY ELECTRON-MICROSCOPY

Incubation with the Bcl-2 antibody before fixation of tissues allowed good localization of the antigenic determinant. We showed that the Bcl -2 gene product in centroblastic-centrocytic lymphoma is mainly locali zed on the outer mitochondrial membrane and, to a lesser degree, on th e nuclear envelope, No significant staining was found in other cytopla smic domains. Careful examination also revealed that gold particles di d not recognize an integral membrane epitope, but an antigenic determi nant localized at a short distance from the cytoplasmic side of the me mbrane itself, This observation suggests that, by interacting with oth er cytoplasmic proteins, Bcl-2 plays some role in the cytoplasmic mach inery involved in the regulation of programmed cell death. (C) 1995 Ac ademic Press, Inc.