CD34 is a highly glycosylated type I membrane protein that is selectively expressed on hematopoietic stem cells and vascular endothelium. It has been widely used as a molecular marker for the identification, isolation, and manipulation of hemopoietic stem cells and progenitors. CD34 can function as a regulator of hemopoietic cell adhesion by mediating the attachment of stem cells to bone marrow stromal cells or other bone marrow components. The full length human CD34 is a 385 amino acid protein, consisting of a 31 amino acid signal sequence, a 74 amino acid cytoplasmic domain, a 21 amino acid transmembrane domain and a 259 amino acid extracellular domain. Recombinant Human sCD34 is a 258 amino acid polypeptide containing only the extracellular domain of the full length CD34 protein. The calculated molecular weight of Recombinant Human sCD34 is 27.4 kDa.