Rat protein tyrosine phosphatase eta physically interacts with the PDZ domains of syntenin.

The tyrosine phosphatase r-PTPη is able to suppress the malignant phenotype of rat thyroid tumorigenic cell lines. To identify r-PTPη interacting proteins, a yeast two-hybrid screening was performed and an insert corresponding to the full-length syntenin cDNA was isolated. It encodes a protein containing two PDZ domains that mediates the binding of syntenin to proteins such as syndecan, proTGF-α, β-ephrins and neurofascin. We show that r-PTPη is able to interact with syntenin also in mammalian cells, and although syntenin is a tyrosine-phosphorylated protein it is not a substrate of r-PTPη. The integrity of both PDZ domains of syntenin and the carboxy-terminal region of r-PTPη are required for the interaction between syntenin and r-PTPη.