Cluster Of Differentiation 109 (CD109)

CD109 is a GPI-linked cell surface antigen expressed by CD34 acute myeloid leukemia cell lines, T-cell lines, activated T lymphoblasts, endothelial cells, and activated platelets (Lin et al., 2002). In addition, the platelet-specific Gov antigen system, implicated in refractoriness to platelet transfusion, neonatal alloimmune thrombocytopenia, and posttransfusion purpura, is carried by CD109 (Kelton et al., 1990; Lin et al., 2002).

CD109 encodes a deduced 1,445-amino acid protein with a predicted molecular mass of approximately 162 kD. The protein contains a cleavable 21 residue N-terminal sequence, 17 potential N-linked glycosylation sites, a GPI anchor site, and a thioester motif characteristic of the alpha-2-macroglobulin (A2M)/complement (AMCOM) family.