CR2

Complement C3d receptor 2 (CR2), also known as CD21, CVID7, SLEB9, CR C3DR, complement receptor type 2 or Epstein-Barr virus (EBV) receptor, is a 145 kDa transmembrane protein that belongs the receptors of complement activation (RCA) family. Mature human CD21 is 1013 amino acids (aa) in length, containing a 951-aa extracellular domain (ECD) and a short 34-aa cytoplasmic tail. It is reported that the ECD of human CD21 shares 71% amino acids identity with mouse CD21 ECD.

CR2 is expressed on mature B and T lymphocytes, pharyngeal epithelial cells, astrocytes and follicular dendritic cells of the spleen. When expressed on mature B cells, CR2 can form a complex with CD19 and CD81, so-called the B cell co-receptor complex, which enhances B cell response to the antigen. In addition, this protein is involved in Epstein-Barr virus (EBV) infections and it functions as a receptor for this virus binding on B cells and T cells.

Gene ID: 1380
UniProt ID: P20023