complement C3b/C4b receptor 1 (Knops blood group)
The information on this page was automatically extracted from online scientific databases.
From NCBI Gene:
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. [provided by RefSeq, Jul 2008]
(Microbial infection) Acts as a receptor for Epstein-Barr virus.
Membrane immune adherence receptor that plays a critical role in the capture and clearance of complement-opsonized pathogens by erythrocytes and monocytes/macrophages (PubMed:2963069). Mediates the binding by these cells of particles and immune complexes that have activated complement to eliminate them from the circulation (PubMed:2963069). Acts also in the inhibition of spontaneous complement activation by impairing the formation and function of the alternative and classical pathway C3/C5 convertases, and by serving as a cofactor for the cleavage by factor I of C3b to iC3b, C3c and C3d,g, and of C4b to C4c and C4d (PubMed:2972794, PubMed:8175757). Plays also a role in immune regulation by contributing, upon ligand binding, to the generation of regulatory T cells from activated helper T cells (PubMed:25742728).