<unk> ype<unk>  <unk>  also known as C3b/C4b receptor or CD35 (cluster of differentiation 35) is a protein that in humans is encoded by the<unk>  gene. This gene is a member of the regulators of complement activation (RCA) family and is located in the 'cluster RCA' region of chromosome<unk> . The gene encodes a monomeric single-pass type I membrane glycoprotein found on erythrocytes, leukocytes, glomerular podocytes, hyalocytes, 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. In primates,<unk>  serves as the main system for processing and clearance of complement opsonized immune complexes. It has been shown that<unk>  can act as a negative regulator of the complement cascade, mediate immune adherence and phagocytosis and inhibit both the classic and alternative pathways. The number of<unk>  molecules decreases with aging of erythrocytes in normal individuals and is also decreased in pathological conditions such as systemic lupus erythematosus (SLE), HIV infection, some haemolytic anaemias and other conditions featuring immune complexes. In mice,<unk>  is an alternatively spliced variant of the<unk>  (CR2) gene. Certain alleles of this gene have been statistically associated with an increased risk of developing late-onset Alzheimer's disease.
Complement receptor 1
Complement component 4
Fc receptor-like molecule
Complement component 3
Fc receptor
Complement component 5a
Interleukin-3 receptor
Interleukin-7 receptor