Bcl-2-associated X protein

The Bcl-2–associated X protein, or BAX, gene was the first identified pro-apoptotic member of the Bcl-2 protein family. [

] Bcl-2 family members share one or more of the four characteristic domains of homology entitled the Bcl-2 homology (BH) domains (named BH1, BH2, BH3 and BH4), and can form hetero- or homodimers. Bcl-2 proteins act as anti- or pro-apoptotic regulators that are involved in a wide variety of cellular activities.

BAX is a pro-apoptotic Bcl-2 protein containing BH1, BH2 and BH3 domains. In healthy mammalian cells, the majority of BAX is found in the cytosol, but upon initiation of apoptotic signaling, BAX undergoes a conformation shift, and inserts into organelle membranes, primarily the outer mitochondrial membrane. [

] BAX is believed to interact with, and induce the opening of the mitochondrial voltage-dependent anion channel, VDAC. Alternatively, growing evidence suggest that activated Bax and/or Bak form an oligomeric pore, MAC in the outer membrane. This results in the the release of cytochrome c and other pro-apoptotic factors from the mitochondria, often referred to as mitochondrial outer membrane permeabilization, leading to activation of caspases. This defines a direct role for Bax in mitochondrial outer membrane permeabilization, a role common to the Bcl-2 proteins containing the BH1, BH2 and BH3 domains.

The expression of "BAX" is upregulated by the tumor suppressor protein p53, and BAX has been shown to be involved in p53-mediated apoptosis. The p53 protein is a transcription factor that, when activated as part of the cell's response to stress, regulates many downstream target genes, including "BAX". However, p53 also has a transcription-independent role in apoptosis. In particular, p53 interacts with BAX, promoting its activation as well as its insertion into the mitochondrial membrane.

ee also

* Apoptosis
* Apoptosome
* Bcl-2
* BH3 interacting domain death agonist (BID)
* Caspases
* Cytochrome c
* Noxa
* Mitochondrion
* p53 upregulated modulator of apoptosis (PUMA)

References

Further reading

PBB_Further_reading
citations =
*cite journal | author=Vieira HL, Haouzi D, El Hamel C, "et al." |title=Permeabilization of the mitochondrial inner membrane during apoptosis: impact of the adenine nucleotide translocator. |journal=Cell Death Differ. |volume=7 |issue= 12 |pages= 1146–54 |year= 2001 |pmid= 11175251 |doi= 10.1038/sj.cdd.4400778
*cite journal | author=Buytaert E, Callewaert G, Vandenheede JR, Agostinis P |title=Deficiency in apoptotic effectors Bax and Bak reveals an autophagic cell death pathway initiated by photodamage to the endoplasmic reticulum. |journal=Autophagy |volume=2 |issue= 3 |pages= 238–40 |year= 2007 |pmid= 16874066 |doi=
*cite journal | author=Steele AD, Yi CH |title=Neuromuscular denervation: Bax up against the wall in amyotrophic lateral sclerosis. |journal=J. Neurosci. |volume=26 |issue= 50 |pages= 12849–51 |year= 2007 |pmid= 17171827 |doi=

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