CR2 Gene

CR2 (Complement C3d Receptor 2) is a protein-coding gene located on chromosome 1q32.2. The encoded protein, Complement C3d Receptor 2(CD21), is the receptor for Epstein-Barr virus on human B cells and T cells.

Here, CD21 interacts with three intracellular proteins:

• the p53 protein expressed in human B lymphoma cells
• the p68 calcium binding protein expressed in normal B lymphocytes, and
• the nuclear p120 ribonucleoprotein.

Furthermore, CD21 participates in the activation of B lymphocytes (Barel M et al 1995). Alternatively spliced transcript variants encoding different isoforms have been found for this gene.

The CR2 gene encodes CD21, a membrane protein that acts as a receptor for Epstein-Barr virus (EBV) and binds to B and T lymphocytes. Genetic variations in this gene are associated with susceptibility to systemic lupus erythematosus type 9 (SLEB9).

Diseases associated with CR2 include:

• CVID (Common Variable Immunodeficiency) 7

1. Barel M et al (1995) Binding sites of the Epstein-Barr virus and C3d receptor (CR2, CD21) for its three intracellular ligands, the p53 anti-oncoprotein, the p68 calcium binding protein and the nuclear p120 ribonucleoprotein. Mol Immunol 32:389-397.
2. Carroll MC (1998) CD21/CD35 in B cell activation. Semin Immunol 10:279-286.