The protein encoded by this gene is a member of the protein tyrosine phosphatase (PTP) family. PTPs are known to be signaling molecules that regulate a variety of cellular processes including cell growth; differentiation; mitosis; and oncogenic transformation. This PTP contains an extracellular domain; a single transmembrane segment and two tandem intracytoplasmic catalytic domains; and thus is classified as a receptor type PTP. This PTP has been shown to be an essential regulator of T- and B-cell antigen receptor signaling. It functions through either direct interaction with components of the antigen receptor complexes; or by activating various Src family kinases required for the antigen receptor signaling. This PTP also suppresses JAK kinases; and thus functions as a regulator of cytokine receptor signaling. Alternatively spliced transcripts variants of this gene; which encode distinct isoforms; have been reported.