Complement Receptor 4
Complement receptor 4 (CR4), also called p150,95, pairs the CD11c (ITGAX) alpha subunit with the common beta-2 chain CD18, making it a close relative of CR3 with partially overlapping but distinct biology. CR4 is prominent on dendritic cells, macrophages, monocytes and granulocytes, where it binds iC3b and supports phagocytosis of opsonized targets, cell adhesion and migration. Its expression level is a standard marker used to identify and sort conventional dendritic cells. Compared with CR3, CR4 shows different ligand preferences and tissue distribution, and it contributes to pathogen uptake and immune-complex handling. Recombinant CR4 protein is useful for ligand-binding, blocking and dendritic-cell studies.
