Source : Escherichia Coli. BCA 1 Human Recombinant produced in E.Coli is a single, non-glycosylated polypeptide chain topological domain containing 110 amino acids (23-109 a.a) & having a molecular mass of 12.7kDa. BCA 1 is fused to a 23 amino acid His-tag at N-terminus. BCA-1 is a CXC chemokine that is highly expressed in thesecondary lymphoid organs, such as follicles of the spleen, lymph nodes, & Peyer's patches. CXCL13 promotes the migration of B lymphocytes (compared to T cells & macrophages), by stimulating calcium influx into, & chemotaxis of, cells expressing Burkitt's lymphoma receptor 1 (BLR1). BCA1 therefore function in the homing of B lymphocytes to follicles. Human BCA-1 shares a 64% amino acid sequence similarity with the mouse protein & 23 - 34% amino acid sequence identity with other known CXC chemokines. Recombinant or chemically synthesized BCA1 is a potent chemoattractant for B lymphocytes but not T lymphocytes, monocytes or neutrophils. BLR1, a G protein-coupled receptor originally isolated from Burkitt's lymphoma cells, has now been shown to be the specific receptor for BCA1. Among cells of the hematopoietic lineages, the expression of BLR-1, now designated CXCR-5, is restricted to B lymphocytes & a subpopulation of T helper memory cells.