Related Experiment Video

Updated: Oct 20, 2025

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

8.1K

Bcl-xL inhibits tBid and Bax via distinct mechanisms

Fabronia Murad1, Ana J Garcia-Saez1,2

  • 1Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany. ana.garcia@uni-koeln.de.

Faraday Discussions
|September 16, 2021
PubMed

Insights

The Bcl-2 protein family regulates apoptosis by controlling protein interactions and intracellular movement. This study reveals how Bcl-xL, Bax, and tBid dynamics at mitochondria dictate cell death.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • The Bcl-2 protein family critically regulates apoptosis, a programmed cell death pathway.
  • These proteins form complex networks influencing mitochondrial permeabilization and cell fate.
  • The precise orchestration of Bcl-2 family member actions remains incompletely understood.

Purpose of the Study:

  • To investigate the orchestration of apoptosis regulation by the Bcl-2 family.
  • To quantitatively analyze the interactions and localization dynamics of Bcl-xL, Bax, and tBid in living cells.

Main Methods:

  • Quantitative analysis of protein interactions in living cells.
  • Tracking the localization dynamics of Bcl-xL, Bax, and tBid between cytosol and mitochondria.
  • Analysis of phospho-mimetic Bcl-xL variants.

Main Results:

  • Bax and tBid constitutively shuttle between cytosol and mitochondria independently.
  • Bcl-xL stabilizes tBid at mitochondria, forming tight complexes.
  • Bcl-xL promotes Bax retrotranslocation to the cytosol via weak inhibitory mitochondrial complexes.
  • Phosphorylation of Bcl-xL appears to regulate its function through multiple mechanisms.

Conclusions:

  • The Bcl-2 network regulates apoptosis not only through protein-protein interactions but also by modulating intracellular localization dynamics.
  • Bcl-xL, Bax, and tBid exhibit distinct localization behaviors that are modulated by their interactions.
  • Understanding these dynamics provides insights into the precise control of apoptosis.

More Related Videos

Myeloid Innate Signaling Pathway Regulation by MALT1 Paracaspase Activity07:09

Myeloid Innate Signaling Pathway Regulation by MALT1 Paracaspase Activity

Published on: January 7, 2019

7.6K
Identifying Inhibitors of the HBx-DDB1 Interaction Using a Split Luciferase Assay System05:55

Identifying Inhibitors of the HBx-DDB1 Interaction Using a Split Luciferase Assay System

Published on: December 21, 2019

6.9K

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...
7.1K
NF-κB-dependent Signaling Pathway02:26

NF-κB-dependent Signaling Pathway

The transcription factor NF-κB was discovered in 1986 in the lab of Nobel laureate Professor David Baltimore, for its interaction with the immunoglobulin light chain enhancer in B-cells. After more than three decades of study, it is now evident that NF-κB regulates the expression of over 100 genes. Most of these genes play an essential role in the innate and adaptive immune responses as well as the inflammatory responses of animals.
NF-κB-dependent Signaling Mechanism
The...
7.9K
TGF - β Signaling Pathway01:16

TGF - β Signaling Pathway

The TGF-β signaling pathway regulates cell growth, differentiation, adhesion, motility, and development. TGF-β ligands that induce TGF-β signaling are synthesized in their latent form. Several proteases or cell surface receptors such as integrins act upon the latent form, releasing the active ligand. There are three types of mammalian TGF-βs: (TGF-β1, TGF-β2, and TGF-β3) that bind as homodimers or heterodimers to TGF-β receptors. The TGF-β receptors...
8.0K
Defense Against Bacterial Pathogens01:31

Defense Against Bacterial Pathogens

The human immune system is a complex network of cells, tissues, and organs that work together to defend the body against bacterial infections. It consists of various immune cells, each playing a specific role in the defense mechanism.
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...
1.7K
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...
6.8K
B Cell Activation and Differentiation01:24

B Cell Activation and Differentiation

The adaptive immune response, a sophisticated defense mechanism, relies on the activation and differentiation of B lymphocytes, or B cells. These processes enable our bodies to mount a tailored response against specific pathogens such as bacteria, free virus particles, toxins, and parasites.
When naive B cells encounter a specific antigen that can bind to the B cell receptor (BCR) on their surface, they undergo sensitization to respond to the antigen's presence. Sensitization begins with...
11.1K