Bcl-2-associated X Protein

Bcl-2-associated X Protein

Identifiers Symbols BAX; BCL2L4 External IDs OMIM: 600040 MGI: 99702 HomoloGene: 7242 ChEMBL: 5318 GeneCards: BAX Gene

Gene Ontology
Molecular function	• protein binding • lipid binding • channel activity • identical protein binding • protein homodimerization activity • protein heterodimerization activity • BH3 domain binding
Cellular component	• nucleus • mitochondrion • mitochondrial outer membrane • mitochondrial permeability transition pore complex • endoplasmic reticulum • endoplasmic reticulum membrane • cytosol • cytosolic part • pore complex • Bcl-2 family protein complex
Biological process	• response to acid • ovarian follicle development • neuron migration • T cell homeostatic proliferation • B cell homeostasis • B cell apoptotic process • kidney development • release of cytochrome c from mitochondria • protein insertion into mitochondrial membrane involved in apoptotic signaling pathway • blood vessel remodeling • myeloid cell homeostasis • B cell negative selection • B cell homeostatic proliferation • positive regulation of B cell apoptotic process • apoptotic DNA fragmentation • glycosphingolipid metabolic process • regulation of nitrogen utilization • apoptotic process • induction of apoptosis • activation of cysteine-type endopeptidase activity involved in apoptotic process • cleavage of lamin involved in execution phase of apoptosis • transformed cell apoptotic process • response to DNA damage stimulus • germ cell development • mitochondrial fusion • activation of cysteine-type endopeptidase activity involved in apoptotic process by cytochrome c • apoptotic mitochondrial changes • fertilization • response to toxin • response to salt stress • establishment or maintenance of transmembrane electrochemical gradient • response to gamma radiation • virus-host interaction • hypothalamus development • cerebral cortex development • nuclear fragmentation involved in apoptotic nuclear change • negative regulation of protein binding • positive regulation of protein oligomerization • reduction of endoplasmic reticulum calcium ion concentration • release of matrix enzymes from mitochondria • negative regulation of peptidyl-serine phosphorylation • regulation of mammary gland epithelial cell proliferation • cellular response to UV • limb morphogenesis • germ cell programmed cell death • odontogenesis of dentin-containing tooth • positive regulation of apoptotic process • regulation of protein homodimerization activity • regulation of protein heterodimerization activity • negative regulation of neuron apoptotic process • positive regulation of neuron apoptotic process • mitochondrial fragmentation involved in apoptotic process • development of secondary sexual characteristics • retinal cell programmed cell death • positive regulation of developmental pigmentation • negative regulation of fibroblast proliferation • spermatid differentiation • post-embryonic camera-type eye morphogenesis • response to axon injury • homeostasis of number of cells within a tissue • protein oligomerization • protein homooligomerization • positive regulation of release of sequestered calcium ion into cytosol • neuron apoptotic process • regulation of cell cycle • regulation of mitochondrial membrane potential • Sertoli cell proliferation • retina development in camera-type eye • positive regulation of apoptotic process involved in mammary gland involution • vagina development • intrinsic apoptotic signaling pathway in response to endoplasmic reticulum stress • cellular response to organic substance • positive regulation of release of cytochrome c from mitochondria • apoptotic signaling pathway • intrinsic apoptotic signaling pathway • positive regulation of endoplasmic reticulum unfolded protein response • positive regulation of intrinsic apoptotic signaling pathway
Sources: Amigo / QuickGO

RNA expression pattern More reference expression data Orthologs Species Human Mouse Entrez 581 12028 Ensembl ENSG00000087088 ENSMUSG00000003873 UniProt Q07812 Q07813 RefSeq (mRNA) NM_004324.3 NM_007527.3 RefSeq (protein) NP_004315.1 NP_031553.1 Location (UCSC) Chr 19:
49.46 – 49.47 Mb Chr 7:
45.46 – 45.47 Mb PubMed search

The Bcl-2–associated X protein, or Bax is a protein of the Bcl-2 gene family. It promotes apoptosis by competing with Bcl-2 proper.

The 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. Orthologs of the BAX gene have been identified in most mammals for which complete genome data are available.

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 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. Wild-type p53 has been demonstrated to upregulate the transcription of a chimeric reporter plasmid utilizing the consensus promoter sequence of BAX approximately 50-fold over mutant p53. Thus it is likely that p53 promotes BAX's apoptotic faculties in vivo as a primary transcription factor. 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.