title: Membrane topology of the Bcl-2 proto-oncogenic protein demonstrated in vitro.
abstract: The Bcl-2 oncogenic protein was synthesized in vitro and shown to post-translationally integrate asymmetrically into microsomal membranes with no requirement for an amino-terminal signal sequence. Instead, a carboxyl-terminal hydrophobic domain of Bcl-2 served as an insertion sequence essential for membrane assembly since a Bcl-2 mutant lacking this domain completely lost its ability to associate with microsomal membranes. The data demonstrate that Bcl-2 is tightly associated with the lipid bilayer with the nature of an integral membrane protein. The membrane orientation of Bcl-2 was determined using a protease protection assay, which showed that it is predominantly localized to the cytoplasmic face of membranes. A similar type of membrane processing has been shown for cytochrome b5 and also suggested for the viral oncogenic protein polyoma middle-T antigen.
authors.affiliation: Department of Pathology, Stanford University School of Medicine, California 94305.
authors.forename: Z
authors.initials: Z
authors.lastname: Chen-Levy
authors.forename: M L
authors.initials: ML
authors.lastname: Cleary
mesh_terms: D000818:Animals; D007425:Intracellular Membranes / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics; D008861:Microsomes / Q000378:metabolism; D009154:Mutation; D014176:Protein Biosynthesis; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D011505:Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D014158:Transcription, Genetic
chemical_list: D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011505:Protein-Tyrosine Kinases