LILRB3 is a 631 amino acid type I transmembrane glycoprotein, which contains four immunoreceptor tyrosine-based inhibition motif (ITIM) sequences within a long cytoplasmic tail. Phosphorylation of the tyrosine residues within ITIMs is known to enable the binding and activation of protein tyrosine phosphatases, which act as cell signaling modulators and inhibitors of cell activation. LILRB3 may act as receptor for class I MHC antigens.