Antigens, CD45

High-Molecular Weight Glycoproteins uniquely expressed on the surface of Leukocytes and their hemopoietic progenitors. They contain a cytoplasmic Protein Tyrosine Phosphatase activity which plays a Role in intracellular signaling from the Cell Surface Receptors. The CD45 Antigens occur as multiple Isoforms that result from alternative mRNA splicing and differential usage of three Exons.