Assembly of Bcl-2 into microsomal and outer mitochondrial membranes

• Published in: The Journal of biological chemistry Vol. 269; no. 13; pp. 9842 - 9849
• Main Authors: JANIAK, F, LEBER, B, ANDREWS, D. W
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 01.04.1994
• Subjects: Animals; Animals, Newborn; Biological and medical sciences; Cell physiology; Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes; Cytochromes b5 - biosynthesis; Cytochromes b5 - isolation & purification; Dogs; Fundamental and applied biological sciences. Psychology; Intracellular Membranes - metabolism; Liposomes; Membrane Proteins - biosynthesis; Membrane Proteins - isolation & purification; Microsomes - metabolism; Mitochondria, Heart - metabolism; Mitochondria, Liver - metabolism; Molecular and cellular biology; Pancreas - metabolism; Protein Biosynthesis; Protein-Tyrosine Kinases - biosynthesis; Proto-Oncogene Proteins - biosynthesis; Proto-Oncogene Proteins - isolation & purification; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogenes; Rats; Rats, Sprague-Dawley; Recombinant Fusion Proteins - biosynthesis; Recombinant Fusion Proteins - isolation & purification; Submitochondrial Particles - metabolism; Mitochondria; Cytochrome b; C terminal peptide; Molecular assembly; Biomembrane; Hydrophobic site; Microsome; Protooncogene
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(17)36960-0

Bcl-2 is thought to associate spontaneously with membranes via a carboxyl-terminal hydrophobic domain by a mechanism analogous to that of cytochrome b5. We have examined the association of Bcl-2 with a variety of highly purified intracellular membranes in vitro. Fusion proteins were used to assess directly the role of the carboxyl-terminal hydrophobic domain of Bcl-2 in membrane association. Although this domain of Bcl-2 was sufficient to promote the association of a normally cytosolic polypeptide with either microsomal or mitochondrial membranes additional nonhydrophobic amino-terminal residues were required for membrane integration. Furthermore, direct comparison of membrane binding of Bcl-2 and cytochrome b5 revealed that similar to cytochrome b5, membrane targeting of Bcl-2 was not dependent on protease-sensitive components of the recipient membranes. In competition experiments, cytochrome b5 demonstrated the expected preference for integration into endoplasmic reticulum membranes. In contrast, the data presented here suggest that Bcl-2 is targeted to the cytoplasmic surface of multiple intracellular membranes, both in vitro and in human leukemic cells.