Figure 3.

Structure and interaction of CD47 and SIRPα. CD47 contains one N-terminal extracellular IgV-like domain and five-membrane-spanning segments at the membrane. SIRPα, as the CD47 ligand, contains three extracellular IgSF domains, one transmembrane spanning region and an intracellular domain with ITIM motifs. CD47-SIRPα binding prevents the host cell from being targeted for phagocytosis, while anti-CD47 antibodies can block the suppression signal and promote phagocytosis by macrophages (27). CD47, cluster of differentiation 47; ITIM, immunoreceptor tyrosine-based inhibitory motif; SIRPα, signal-regulatory protein α.