Tags: Protein.
Complement receptor type 2 (Cr2) also known as complement C3d receptor Epstein-Barr virus receptor and CD21 (cluster of differentiation 21) is a protein that in humans is encoded by the CR2 gene.Cr2 is involved in the complement system. It binds to iC3b (inactive derivative of C3b) C3dg or C3d. B cells have Cr2 receptors on their surfaces allowing the complement system to play a role in B-cell activation and maturation