Structure and Function of the Complement Receptors, CR1 (CD35) and CR2 (CD21)

doi:10.1016/S0065-2776(08)60654-9

Advances in Immunology

Volume 46, 1989, Pages 183-219

https://doi.org/10.1016/S0065-2776(08)60654-9 Get rights and content

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This chapter reports recent findings regarding two of these receptors, complement receptor type 1 (CR1; CD35) and complement receptor type 2 (CR2; CD21), which bind the cleavage fragments of C4 and C3 that are covalently attached to activators of the complement system. The complete primary structure of CR1 is now known through molecular cloning studies. The most common allotype of CR1, the F or A allotype, is a polypeptide of 2039 residues: A 41-amino acid signal peptide, an extracellular domain of 1930 residues, a 25-amino acid transmembrane region, and a 43-amino acid cytoplasmic domain. The extracellular portion of the receptor is composed exclusively of 30 short consensus repeats (SCRs). Each SCR contains 60 to 70 amino acids, six of which are found in all SCRs: Four cysteines, a single tryptophan between the third and fourth cysteine, and a glycine after the second cysteine. The primary protein structure of CR2 has been determined through analysis of the nucleotide sequences of clones isolated from human tonsillar and Raji lymphoblastoid cell line cDNA libraries. These clones encode a 20-amino acid signal peptide, a 954-residue extracellular domain, a 24-amino acid transmembrane region, and a 34-amino acid cytoplasmic domain. The extracellular domain is composed entirely of 15 tandem short consensus repeat sequences that are homologous to those described in CR1 and other C3/C4-binding proteins, as well as in some membrane proteins that do not share this function. The molecular cloning of CR1 enabled the construction of eukaryotic expression vectors containing cDNA inserts, representing the entire CR1 coding sequence and various deletion mutants. The expression of these recombinant forms of CR1, and the analysis of their ligand binding function has led to the identification of distinct C3b and C4b recognition sites. These functional domains have been assigned to specific structural elements of the receptor, the SCR and the LHR. The functions of CR2 have been more difficult to define fully than has its structure. The experimental evidence to date suggests that this single transmembrane glycoprotein may have several important immunoregulatory.

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Structure and Function of the Complement Receptors, CR1 (CD35) and CR2 (CD21)

Publisher Summary

Clin. Immunol. Immunopathol.

FEBS Lett.

Blood

Cell

Cell. Immunol.

Mol. Immunol.

Exp. Cell Res.

J. Biol. Chem.

J. Biol. Chem.

Lab. Invest.

Proc. Natl. Acad. Sci. U.S.A.

Biochem. J.

J. Immunol.

J. Clin. Invest.

J. Exp. Med.

J. Immunol.

J. Immunol.

Biochem. J.

Proc. Natl. Acad. Sci. U.S.A.

J. Immunol.

Science

J. Exp. Med.

J. Immunol.

J. Exp. Med.

J. Exp. Med.

J. Immunol.

J. Cell Biol.

Immunol. Rev.

Nature (London)

J. Exp. Med.

J. Immunol.

J. Exp. Med.

J. Immunol.

Biochemistry

Biochem. J.

J. Immunol.

J. Immunol.

Scand. J. Immunol.

Scand. J. Immunol.

Ann. Rev. Immunol.

J. Clin. Invest.

J. Immunol.

FASEB J.

Surgery

Proc. Natl. Acad. Sci. U.S.A.

Eur. J. Immunol.

J. Immunol.

Proc. Natl. Acad. Sci. U.S.A.

J. Exp. Med.

J. Exp. Med.