The gene encodes a monomeric single-pass type I membrane glycoprotein found on erythrocytes, leukocytes, glomerular podocytes, hyalocytes, and splenic follicular dendritic cells.

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.

[3] In primates, CR1 serves as the main system for processing and clearance of complement opsonized immune complexes.

It has been shown that CR1 can act as a negative regulator of the complement cascade, mediate immune adherence and phagocytosis and inhibit both the classic and alternative pathways.

A transcript with an open reading frame of 4,224 nucleotides encodes the long isoform, CR1; this is predicted to be a protein of 1,408 amino acids that includes 21 short consensus repeats (SCR) of ca.

[10] The most common allelic variant of the human CR1 gene (CR1*1) is composed of 38 exons spanning 133kb encoding a protein of 2,039 amino acids with a predicted molecular weight of 220 kDa.

Large insertions and deletions have given rise to four structurally variant genes and some alleles may extend up to 160 kb and 9 additional exons.

The LHR seem to have arisen as a result of unequal crossing over and the event that gave rise to LHR-B seems to have occurred within the fourth exon of either LHR-A or –C.

Curiously the human CR1 gene appears to have an unusual protein conformation but the significance of this finding is not clear.

This 'stickiness', known as rosetting, is believed to be a strategy used by the parasite to remain sequestered in the microvasculature to avoid destruction in the spleen and liver.

This article incorporates text from the United States National Library of Medicine, which is in the public domain.