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Bad, a heterodimeric partner for Bcl-XL and Bcl-2, displaces Bax and promotes cell death

E Yang1, J Zha, J Jockel

  • 1Howard Hughes Medical Institute, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.

Cell
|January 27, 1995
PubMed

Insights

Researchers identified a novel protein, Bad, that interacts with Bcl-xL and Bcl-2, influencing cell death pathways. Bad

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • The Bcl-2 family regulates apoptosis, a crucial process in multicellular organisms.
  • Understanding protein interactions within this family is key to deciphering cell death control.

Purpose of the Study:

  • To identify novel proteins interacting with Bcl-2.
  • To characterize the functional role of newly identified interacting proteins in the mammalian cell death pathway.

Main Methods:

  • Yeast two-hybrid screening to identify interacting proteins.
  • Lambda expression cloning for protein identification and characterization.
  • Mammalian cell-based assays to study protein dimerization and apoptosis.

Main Results:

  • A novel protein, Bad, was identified as a Bcl-2 interacting protein.
  • Bad selectively dimerizes with Bcl-xL and Bcl-2, but not Bax or other Bcl-2 family members.
  • Bad binding to Bcl-xL reversed its death repressor activity by displacing Bax, restoring apoptosis.

Conclusions:

  • Bad plays a critical role in regulating apoptosis by modulating Bcl-xL and Bcl-2 activity.
  • The balance of dimerization between Bad, Bcl-xL, Bcl-2, and Bax determines cellular susceptibility to death signals.
  • Bad levels influence the efficacy of Bcl-2 and Bcl-xL in repressing cell death.

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