Related Experiment Video

Updated: Jul 13, 2026

Examining BCL-2 Family Function with Large Unilamellar Vesicles
08:35

Examining BCL-2 Family Function with Large Unilamellar Vesicles

Published on: October 5, 2012

Comparative biophysical characterization of p53 with the pro-apoptotic BAK and the anti-apoptotic BCL-xL

Begona Sot1, Stefan M V Freund, Alan R Fersht

  • 1Medical Research Council, Centre for Protein Engineering, Hills Road, Cambridge CB2 0QH, United Kingdom.

The Journal of Biological Chemistry
|August 19, 2007
PubMed

Insights

The tumor suppressor p53 protein interacts with Bcl-x(L) and Bak proteins in mitochondria. P53 binds Bcl-x(L) more strongly than Bak, with distinct binding sites on the p53 core domain.

Area of Science:

  • Molecular Biology
  • Biophysics
  • Cell Biology

Background:

  • The tumor suppressor p53 protein plays a critical role in apoptosis, particularly in radiosensitive tissues.
  • Transcription-independent apoptosis involves p53's interaction with Bcl-2 family proteins in mitochondria.

Purpose of the Study:

  • To characterize the interaction between p53 and the pro-apoptotic Bak protein and the anti-apoptotic Bcl-x(L) protein.
  • To compare the binding affinity and interaction surfaces of p53 with Bak and Bcl-x(L).

Main Methods:

  • Biophysical techniques including fluorescence anisotropy, analytical ultracentrifugation, and Nuclear Magnetic Resonance (NMR) spectroscopy.
  • Characterization of protein-protein interactions and binding site mapping.

Main Results:

  • Both Bak and Bcl-x(L) interact exclusively with the p53 core domain, not its terminal regions.
  • p53 exhibits higher binding affinity for Bcl-x(L) than for Bak, supporting sequential binding models.
  • Interactions are electrostatic, but binding sites differ: Bcl-x(L) binds to the p53 DNA-binding site, while Bak does not.

Conclusions:

  • p53's interaction with Bak and Bcl-x(L) is mediated by the p53 core domain.
  • Differential affinities and distinct binding sites suggest specific roles in regulating mitochondrial apoptosis.
  • A novel interaction surface for Bak on p53 is proposed, warranting further investigation.

More Related Videos

Procedure and Key Optimization Strategies for an Automated Capillary Electrophoretic-based Immunoassay Method09:32

Procedure and Key Optimization Strategies for an Automated Capillary Electrophoretic-based Immunoassay Method

Published on: September 10, 2017

Identifying Protein-protein Interaction Sites Using Peptide Arrays07:44

Identifying Protein-protein Interaction Sites Using Peptide Arrays

Published on: November 18, 2014

Related Concept Videos

The Intrinsic Apoptotic Pathway01:31

The Intrinsic Apoptotic Pathway

Internal cellular stress, such as cellular injury or hypoxia, triggers intrinsic apoptosis. The B-cell lymphoma 2 (Bcl-2) family of proteins are the primary regulators of the intrinsic apoptotic pathway. For example, during DNA damage, checkpoint proteins, such as Ataxia Telangiectasia Mutated (ATM protein) and Checkpoints Factor-2 (Chk2) proteins, are activated. These proteins phosphorylate p53 which further activates pro-apoptotic proteins, such as Bax, Bak, PUMA, and Noxa, and inhibits...
Abnormal Proliferation02:23

Abnormal Proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...
Cellular Injury V: Apoptosis and Autophagy01:22

Cellular Injury V: Apoptosis and Autophagy

Cells respond to damage and stress through highly coordinated processes that decide whether they survive or undergo controlled self-destruction. Two major pathways involved in this regulation are apoptosis, a type of programmed cell death, and autophagy, a survival mechanism that helps cells adapt to adverse conditions.ApoptosisApoptosis removes aged or injured cells to maintain tissue balance. During this process, the cell shrinks, chromatin condenses and fragments, and membrane-bound...
The Extrinsic Apoptotic Pathway01:17

The Extrinsic Apoptotic Pathway

The extrinsic apoptotic pathway is initiated when extracellular death-inducing signals, such as specific cytokines, activate the death receptors expressed on the cell surface. The immune cells involved in this pathway are natural killer cells (NK cells) and cytotoxic T-lymphocytes. NK cells are critical in innate immune response, while cytotoxic T-lymphocytes are associated with adaptive immune response. These cells recognize specific receptors expressed on the altered cells and activate...