Siglec-8, also known as SAF, is an approximately 75 kDa transmembrane glycoprotein in the Siglec family of sialic acid-binding immune regulatory molecules. Mature human Siglec-8 consists of a 347 amino acid (aa) extracellular domain (ECD) with three Ig-like domains.Putative adhesion molecule that mediates sialic-acid dependent binding to red blood cells. Preferentially binds to alpha-2,3-linked sialic acid. Also binds to alpha-2,6-linked sialic acid.