Human secreted CD33, also known as Sialic Acid Binding Ig Like Lectin 3, Gp67 and Myeloid Cell Surface Antigen CD33, GenBank Accession No. NM_001772, a.a. 1-259, fused at the C-terminus of the Fc portion of human IgG1, with C-terminal Avi-tag™, expressed in a HEK293 cell expression system. MW = 57 kDa.