Putative adhesion molecule that mediates sialic-acid dependent binding to red blood cells (PubMed:10856141, PubMed:10625619). Preferentially binds to alpha-2,3-linked sialic acid. Also binds to alpha-2,6-linked sialic acid. The sialic acid recognition site may be masked by cis interactions with sialic acids on the same cell surface (PubMed:10625619). Recognizes simultaneously epitopes having a terminal N-acetylneuraminic acid (sialic acid) and an underlying 6-O-sulfated galactose. Preferentially binds to Gal-6-sulfated sialyl-Lewis X glycan epitopes (PubMed:27357658). Expressed specifically on red blood cells namely basophil, mast cells and eosinophils. Contains 1 copy of a cytoplasmic motif that is referred to as the immunoreceptor tyrosine-based inhibitor motif (ITIM). This motif is involved in modulation of cellular responses. The phosphorylated ITIM motif can bind the SH2 domain of several SH2-containing phosphatases. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay. Belongs to the immunoglobulin superfamily. SIGLEC (sialic acid binding Ig-like lectin) family. Siglec-8