Leukocyte common antigen precursor (EC 3.1.3.48) (L-CA) (T200) (CD45 antigen); Required for T-cell activation through the antigen receptor. The first PTPase domain has enzymatic activity, while the second one seems to affect the substrate specificity of the first one. Upon T-cell activation, recruits an dephosphorylates SKAP1 and FYN (1172 aa)