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. 2020 Jan 28;11:18. doi: 10.3389/fimmu.2020.00018

Figure 1.

Figure 1

Structure and interaction of CD47 and SIRPα. (A) CD47 contains one N-terminal extracellular IgV-like domain and five transmembrane spanning segments. SIRPα contains three extracellular IgSF domains, one transmembrane spanning region, and an intracellular domain with ITIM motifs. After the binding of CD47 to SIRPα, two ITIMs in the cytoplasmic tail of SIRPα become phosphorylated then recruit and activate phosphatases including SHP-1 and SHP-2. Ultimately, CD47-SIRPα binding inhibits the host cell from being targeted for phagocytosis, while anti-CD47 antibodies can block the suppression signal and promote phagocytosis (18). (B) The anti-SIRPα antibody, KWAR23 (depicted as ribbons), binds SIRPα at an epitope overlapping with the CD47/SIRPα interface (19). Abbreviations: CD47, cluster of differentiation 47; ITIM, immunoreceptor tyrosine-based inhibitory motif; SHPS-1/2, protein tyrosine phosphatase substrate-1/2; SIRPα, signal-regulatory protein α.