PTP alpha

PTP alpha (PTPRA) is a classical receptor-type protein tyrosine phosphatase with a single transmembrane segment, a compact extracellular region containing a MAM-like module, and two tandem intracellular catalytic domains. The membrane-proximal D1 domain provides the dominant activity and binds substrates including the C-terminal inhibitory tyrosine of Src family kinases, positioning PTP alpha as a positive regulator of Src and Fyn signaling. Through this axis it influences integrin signaling, insulin responses, cell proliferation, and neuronal development. PTP alpha also associates with GRB2 and has been implicated in tumorigenesis, where increased expression sustains Src-dependent transformation. Recombinant forms are used to dissect domain-specific phosphatase mechanisms.