CD33 is a symbol for the gene, CD33 molecule, in humans. Other names include: Myeloid cell surface antigen CD33; Sialic acid-binding Ig-like lectin 3; Siglec-3; gp67; CD antigen CD33; sialic acid binding Ig-like lectin 3; SIGLEC3; p67. The encoded protein has an amino acid length of 364 and a mass of 39.8 kDa. Other isoforms may exist. CD33 is a member of the Immunoglobulin superfamily, SIGLEC (sialic acid binding Ig-like lectin) family. This gene shares homology with other species, including: Mouse, Rat.