Paired box protein Pax-5 (PAX5)

Paired box protein Pax-5 is a transcription factor encoded by the PAX5 gene, which is essential for B-cell lineage commitment and identity. It regulates the expression of B-lineage-specific genes while repressing alternative lineage programs, acting as both a transcriptional activator and repressor. PAX5 is a member of the PAX family and features a conserved DNA-binding paired box domain. It is critical for progression beyond the pro-B cell stage in B lymphopoiesis and is further involved in neural development and spermatogenesis. Alterations in PAX5 expression or function—such as mutations or chromosomal translocations—are closely associated with various B-cell malignancies, especially B-cell acute lymphoblastic leukemia (B-ALL) and Hodgkin's lymphoma. Up to 97% of Reed–Sternberg cells in Hodgkin’s lymphoma express PAX5. PAX5 operates within a transcription factor network with proteins such as IKZF1 and RUNX1, contributing to both normal immune cell function and malignant transformation. PAX5 is widely used as a biomarker in diagnosing and studying B-cell lineage leukemias and lymphomas.

Other names

B-cell lineage specific activator proteinBSAPpaired box gene 5transcription factor PAX-5