Receptor for complement C3, for the Epstein-Barr virus on human B-cells and T-cells and for HNRNPU (PubMed:7753047). Participates in B lymphocytes activation (PubMed:7753047). (Microbial infection) Acts as a receptor for Epstein-Barr virus. Interacts (via Sushi domain 1 and 2) with C3 (PubMed:11387479, PubMed:21527715). Interacts with CD19 (PubMed:1702139). Part of a complex composed of CD19, CR2/CD21, CD81 and IFITM1/CD225 in the membrane of mature B-cells (PubMed:1383329). (Microbial infection) Interacts with Epstein-Barr virus gp350 protein. Mature B-lymphocytes, T-lymphocytes, pharyngeal epithelial cells, astrocytes and follicular dendritic cells of the spleen. Disease susceptibility is associated with variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the receptors of complement activation (RCA) family.