CD45 has been identified as a transmembrane glycoprotein, broadly expressed among hematopoietic cells.CD45 functions as a phosphotyrosine phosphatase, a vital component for efficient tyrosine phosphorylation induction by the TCR/CD3 complex. The tyrosine phosphatase activity of CD45 is contained within the conserved intracellular domain. Src family kinases required for the antigen receptor signaling. Several members of Src and Syk families, including Lck, Fyn and ZAP-70, have been implicated as physiological substrates of CD45.
