Recombinant human BCA1 (B cell- attracting chemokine 1), also known as CXCL13 or BLC, is a disulfide-linked monomeric protein consisting of 88 a.a. and migrates as an approximately 10 kDa protein under reducing and non-reducing conditions. Human CXCL13, generated by the proteolytic removal of the signal peptide and propeptide, has a calculated molecular mass of ~10 kDa. Optimized DNA sequence encoding human BCA1 mature domain was expressed in E. coli.