CD35 (CR1, Complement Receptor 1) is a cell membrane-bound, monomeric glycoprotein and its primary function is to serve as the cellular receptor for C3b and C4b, the most important components of the complement system leading to clearance of foreign macromolecules. CD35 protein mediates cellular binding to particles and immune complexes that have activated complement. The CD35 complex is four different allotypes (C,A,B,D) C is 160 kDa; A is 190 kDa; B is 220 kDa and D is 250 kDa. CD35 is involved in the processing of immune complexes, promoting of binding and phagocytosis of C3b complexes and inhibition of complement activation. CD35 is on neutrophils, eosinophils, monocytes, B-cells, some NK-cells, erythrocytes, myeloid leukemias, follicular dendritic reticulum cells and is negative on basophils. Decreases in expression of CD35 protein and/or mutations in its gene have been associated with gallbladder carcinomas, mesangiocapillary glomerulonephritis, systemic lupus erythematosus and sarcoidosis. Mutations in the CD35 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 of CD35 have been characterized. An additional secreted form of CD35 have also been described but has not been fully characterized.
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Protein Aliases: C3-binding protein; C3b/C4b receptor; CD35; CD35 antigen; complement component (3b/4b) receptor 1 (Knops blood group); complement component receptor 1; Complement receptor type 1; Knops blood group antigen
Gene Aliases: C3BR; C4BR; CD35; CR1; KN
UniProt ID: (Human) P17927
Entrez Gene ID: (Human) 1378