The phosphotyrosine-binding domain (PTB, also phosphotyrosine-interaction or PI domain) in the protein tensin tends to be found at the C-terminus. Tensin is a multi-domain protein that binds to actin filaments and functions as a focal-adhesion molecule (focal adhesions are regions of plasma membrane through which cells attach to the extracellular matrix). Human tensin has actin-binding sites, an SH2 (PfamPF00017) domain and a region similar to the tumour suppressorPTEN. The PTB domain interacts with the cytoplasmic tails of beta integrin by binding to an NPXY motif.
^Eck MJ, Dhe-Paganon S, Trub T, Nolte RT, Shoelson SE (May 1996). "Structure of the IRS-1 PTB domain bound to the juxtamembrane region of the insulin receptor". Cell85 (5): 695–705. doi:10.1016/S0092-8674(00)81236-2. PMID8646778.
^Zhou MM, Huang B, Olejniczak ET, Meadows RP, Shuker SB, Miyazaki M, Trub T, Shoelson SE, Fesik SW (April 1996). "Structural basis for IL-4 receptor phosphopeptide recognition by the IRS-1 PTB domain". Nat. Struct. Biol.3 (4): 388–93. doi:10.1038/nsb0496-388. PMID8599766.