[Structure and function of receptors for C3 cleavage fragments].

Most of the biological effects derived from complement activation depends on interactions between cleavage fragments of complement components and cells bearing specific receptors. This review overviews structure and function of receptors for C3 cleavage fragments. Genes encoding for CR1, CR2 and CR3 have been cloned and they code for integral transmembrane glycoproteins which function as cellular receptors for human C3b, C3dg/C3d and C3bi fragments respectively. These receptors have a wide cellular distribution and participate in transport of immune complexes, phagocytosis and regulation of immune response. Alterations of expression of these molecules are observed in pathology.