PAX5

PAX5

A gene on chromosome 9p13, of which there are multiple isoforms, of which PAX-5A is most studied. It encodes 50-kD B-cell specific activator protein (BSAP), which is expressed in pre-B and mature B cells, but is downregulated/silenced during terminal differentiation of plasma cells under the influence of B-lymphocyte-induced maturation protein-1 (PRDM1). PAX-5A influences the expression of other B-cell specific genes, including CD19 and CD20 and CD79a, preceding the expression of CD20.