C3 binding protein, C3b/C4b receptor, C3BR, C4BR, CD 35, CD35, CD35 antigen, complement component (3b/4b) receptor 1 (Knops blood group), complement component (3b/4b) receptor 1 including Knops blood group system, Complement component receptor 1, Complement receptor 1, Complement receptor type 1, CR 1, CR1, CR1_HUMAN, KN, Knops blood group antigen.
This gene is a member of the receptors of complement activation (RCA) family and is located in the cluster RCA region of chromosome 1. The gene encodes a monomeric single-pass type I membrane glycoprotein found on erythrocytes, leukocytes, glomerular podocytes, and splenic follicular dendritic cells. The Knops blood group system is a system of antigens located on this protein. The protein mediates cellular binding to particles and immune complexes that have activated complement. Decreases in expression of this protein and/or mutations in its gene have been associated with gallbladder carcinomas, mesangiocapillary glomerulonephritis, systemic lupus erythematosus and sarcoidosis. Mutations in this gene have also been associated with a reduction in Plasmodium falciparum rosetting, conferring protection against severe malaria. Alternate allele-specific splice variants, encoding different isoforms, have been characterized. Additional allele specific isoforms, including a secreted form, have been described but have not been fully characterized.
