CD320, also known as CD320 antigen isoform 1, belongs to the low-density lipoprotein receptor family, with 2 low-density lipoprotein receptor type A domains separated by a complement-like cysteine-rich region. It binds TC- cobalamin (Cbl) and internalizes the complex by endocytosis. It is known to enhance proliferation of germinal center (GC) B cells and follicular dendritic cells. It augments the proliferation of PC precursors generated by IL-10. It collaborates with CD44 in supporting lymphomagenesis by a Burkitt lymphoma cell line, L3055. Recombinant human CD320, fused to hIgG-His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.