CD33

CD33 is a transmembrane receptor expressed on cells of monocytic/myeloid lineage. It binds sialic acids, therefore is a member of the SIGLEC family of lectins. The extracellular portion of this receptor contains two immunoglobulin domains (one IgV and one IgC2 domain), placing CD33 within the immunoglobulin superfamily. The intracellular portion of CD33 contains immunoreceptor tyrosine-based inhibitory motifs (ITIMs) that are implicated in inhibition of cellular activity.