Gene Information
Gene Symbol
Entrez Gene ID
Gene Name
BCL2-associated X protein
Chromosomal Location
The protein encoded by this gene belongs to the BCL2 protein family. BCL2 family members form hetero- or homodimers and act as anti- or pro-apoptotic regulators that are involved in a wide variety of cellular activities. This protein forms a heterodimer with BCL2, and functions as an apoptotic activator. This protein is reported to interact with, and increase the opening of, the mitochondrial voltage-dependent anion channel (VDAC), which leads to the loss in membrane potential and the release of cytochrome c. The expression of this gene is regulated by the tumor suppressor P53 and has been shown to be involved in P53-mediated apoptosis. Multiple alternatively spliced transcript variants, which encode different isoforms, have been reported for this gene. (provided by RefSeq, Jul 2008)
GeneCards ID
RefSeq mRNA

Gene Ontology (GO)

GO ID Ontology Definition Evidence Reference
GO:0001783 Biological process B cell apoptotic process IDA 15214043
GO:0001836 Biological process Release of cytochrome c from mitochondria IDA 16199525
GO:0006919 Biological process Activation of cysteine-type endopeptidase activity involved in apoptotic process IMP 11350920
GO:0006927 Biological process Transformed cell apoptotic process IMP 10739008
GO:0008053 Biological process Mitochondrial fusion IDA 14769861
Protein Information
Protein Name
Bcl-2-like protein 4 , apoptosis regulator BAX , BCL2L4 , bcl-2-like protein 4 , BCL2-associated X protein, Bcl2-L-4 , BCL2-associated X protein transcript variant delta2 , BCL2-associated X protein omega , bcl2-L-4
Accelerates programmed cell death by binding to, and antagonizing the apoptosis repressor BCL2 or its adenovirus homolog E1B 19k protein. Under stress conditions, undergoes a conformation change that causes translocation to the mitochondrion membrane, leading to the release of cytochrome c that then triggers apoptosis. Promotes activation of CASP3, and thereby apoptosis
Refseq Proteins
Pfam Accession Pfam ID
PF00452 Bcl-2 Apoptosis regulator proteins, Bcl-2 family

Associated Diseases

Diseases References
Endometrial hyperplasia 17030058
Polycystic ovary syndrome (PCOS) 14505758, 9856409

Deregulation of tissue homeostasis in endometria from patients with polycystic ovarian syndrome with and without endometrial hyperplasia.

Villavicencio A, Bacallao K, Gabler F, Fuentes A, Albornoz J, Casals A, Vega M
Institute of Maternal and Child Research, School of Medicine, P.O. Box 226-3, and Pathology Department, San Borja-Arriaran Clinical Hospital, University of Chile, Santiago, Chile.
Gynecol Oncol. 2007 Feb;104(2):290-5. Epub 2006 Oct 9.
Supporting Literature:
PubMed ID Associated gene/s Associated condition Genetic Mutation Diagnostic Criteria Association with PCOS Ethnicity Conclusion
Ki67, Bcl-2,Pro-Caspase-3 and Caspase-3 
Endometrial hyperplasia 
A higher Bcl-2/Bax relative ratio in PCOSE and HPCOSE was observed, in absence of active Caspase-3 and scarce DNA fragmentation in the four groups of endometria studied. 
Estrogen receptor alpha, Bcl-2 
PCOS criteria (Adam et al., 1985) 
An alternating expression of proteins related to cell survival in endometria from PCOSE may potentially be associated with the disruption of their endometrial cell cycle 
p53,BCL2,EGF/TGF alpha 
Further investigation of the pathogenesis of PCOS is needed on the modulation of tumour suppressor and apoptosis genes such as p53, BAX or the APO/FAS system and the over expression of survival genes such as BCL2. 

Unreviewed Literature:

PubMed / PMC ID
Title Type of study
Role of macrophage secretions on rat polycystic ovary: Its effect on apoptosis. 
In vitro 
Effect of HSP10 on apoptosis induced by testosterone in cultured mouse ovarian granulosa cells. 
Animal study 
Altered expression of Bcl-2 and Bax in follicles within dehydroepiandrosterone-induced polycystic ovaries in rats. 
Animal study 


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