Mouse leukocyte common antigen,LCA;CD45 ELI

Protein tyrosine-protein phosphatase required for T-cell activation through the antigen receptor.

Acts as a positive regulator of T-cell coactivation upon binding to DPP4.

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 and dephosphorylates SKAP1 and FYN (By similarity).

Dephosphorylates LYN, and thereby modulates LYN activity.

{ECO:0000250, ECO:0000269|PubMed:10415030}.