title: Direct interaction of Bcl-2 proteins with tubulin.
abstract: A direct interaction between tubulin and several pro-apoptotic and anti-apoptotic members of the Bcl-2 family has been demonstrated by effects on the assembly of microtubules from pure rat brain tubulin. Bcl-2, Bid, and Bad inhibit assembly sub-stoichiometrically, whereas peptides from Bak and Bax promote tubulin polymerization at near stoichiometric concentrations. These opposite effects on microtubule assembly are mutually antagonistic. The BH3 homology domains, common to all members of the family, are involved in the interaction with tubulin but do not themselves affect polymerization. Pelleting experiments with paclitaxel-stabilized microtubules show that Bak is associated with the microtubule pellet, whereas Bid remains primarily with the unpolymerized fraction. These interactions require the presence of the anionic C-termini of alpha- and beta-tubulin as they do not occur with tubulin S in which the C-termini have been removed. While in no way ruling out other pathways, such direct associations are the simplest potential regulatory mechanism for apoptosis resulting from disturbances in microtubule or tubulin function.
authors.affiliation: Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA.
authors.forename: Leslie
authors.initials: L
authors.lastname: Knipling
authors.forename: J
authors.initials: J
authors.lastname: Wolff
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D051023:BH3 Interacting Domain Death Agonist Protein / Q000378:metabolism; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000737:chemistry* / Q000378:metabolism; D051381:Rats; D013696:Temperature; D013997:Time Factors; D014404:Tubulin / Q000737:chemistry* / Q000378:metabolism; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D051025:bcl-Associated Death Protein / Q000378:metabolism
chemical_list: D051023:BH3 Interacting Domain Death Agonist Protein; D010455:Peptides; D019253:Proto-Oncogene Proteins c-bcl-2; D014404:Tubulin; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein