ID:CR1_HUMAN DESCRIPTION: RecName: Full=Complement receptor type 1; AltName: Full=C3b/C4b receptor; AltName: CD_antigen=CD35; Flags: Precursor; FUNCTION: Mediates cellular binding of particles and immune complexes that have activated complement. SUBUNIT: Monomer. SUBCELLULAR LOCATION: Membrane; Single-pass type I membrane protein. TISSUE SPECIFICITY: Present on erythrocytes, leukocytes, glomerular podocytes, and splenic follicular dendritic cells. POLYMORPHISM: CR1 contains a system of antigens called the Knops blood group system. Polymorphisms within this system are involved in malarial rosetting, a process associated with cerebral malaria, the major cause of mortality in Plasmodium falciparum malaria. Common Knops system antigens include McCoy (McC) and Sl(a)/Vil (Kn4, or Swain-Langley; Vil or Villien). Sl(a-) phenotype is more common in persons of African descent and may protect against fatal malaria. POLYMORPHISM: Other polymorphic forms of CR1 contain 23, 37 or 44 Sushi (CCP/SCR) domains instead of the 30 Sushi (CCP/SCR) domains. The most frequent alleles are the F allotype (shown here) and the S allotype (37 repeat Sushi domains). The gene frequencies of the F allotype and S allotype are 0.87 and 0.11 in Caucasians, 0.82 and 0.11 in African Americans, 0.89 and 0.11 in Mexicans. POLYMORPHISM: Genetic variations in CR1 resulting in CR1 deficiency are involved in protection against severe malaria [MIM:611162]. Parasitized red blood cells (RBCs) from children suffering from severe malaria often adhere to complement receptor 1 (CR1) on uninfected RBCs to form clumps of cells known as rosettes. CR1-deficient red blood cells show greatly reduced rosetting and CR1 deficiency occurs in healthy individuals from malaria-endemic regions. SIMILARITY: Belongs to the receptors of complement activation (RCA) family. SIMILARITY: Contains 30 Sushi (CCP/SCR) domains. WEB RESOURCE: Name=dbRBC/BGMUT; Note=Blood group antigen gene mutation database; URL="http://www.ncbi.nlm.nih.gov/gv/mhc/xslcgi.cgi?cmd=bgmut/systems_info&system=knops";
ModBase Predicted Comparative 3D Structure on P17927
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