Breakpoint cluster region-Abelson murine leukemia viral oncogene homolog 1 fusion protein (BCR-ABL1) b3a2 isoform (BCR-ABL1 (p210, b3a2))

BCR-ABL1 is a constitutively active tyrosine kinase resulting from the reciprocal translocation between chromosomes 9 and 22, commonly referred to as the Philadelphia chromosome (NIH, 2023). The b3a2 variant (also known as e14a2) is a specific transcript of the p210 isoform, formed by the fusion of BCR exon 14 and ABL1 exon 2, and is a hallmark of Chronic Myeloid Leukemia (CML) (PubMed, PMID: 30234454). This fusion protein bypasses normal regulatory mechanisms, activating downstream pathways such as PI3K/AKT, JAK/STAT, and RAS/MAPK to drive malignant cell proliferation and survival (UniProt, P00519). Therapeutic management relies heavily on tyrosine kinase inhibitors (TKIs) like imatinib and dasatinib, which target the ATP-binding pocket of the ABL1 domain (StatPearls, 2023). Despite high efficacy, clinical challenges include the development of resistance through point mutations, most notably the T315I gatekeeper mutation, which necessitates the use of third-generation inhibitors or allosteric modulators like asciminib (Wikipedia, 2024). Monitoring the molecular response through quantitative PCR of BCR-ABL1 transcripts is essential for guiding treatment and identifying potential relapse.

Other names

Philadelphia chromosome proteinp210 BCR-ABLe14a2 fusion proteinBCR-ABL tyrosine kinaseBCR-ABL1 p210 isoform

ATP-competitive inhibition of the tyrosine kinase domain and allosteric inhibition of the ABL1 myristoyl pocket.