Description
CD320 is a heavily glycosylated protein that is expressed as a noncovalent dimer in the kidney, placenta, liver, intestine, and secondary lymphoid organs (3 – 5). It functions as an endocytic receptor for circulating complexes of Cobalamin (Vitamin B12) and Transcobalamin II. In the immune system, CD320 is expressed by germinal center B cells and follicular dendritic cells (FDC) and provides a co‑stimulatory signal to B cells during the germinal center reaction (2, 6 – 8). CD320 also cooperates with CD44 in promoting the development of B cell lymphomas.