Receptor Protein-tyrosine Phosphatase RPTPμ Binds to and Dephosphorylates the Catenin p120 ctn *

By G. Zondag, Albert B. Reynolds, W. Moolenaar. Journal of Biological Chemistry, 2000

127 citations recorded by the source corpus.

RPTPμ is a prototypic receptor-like protein-tyrosine phosphatase (RPTP) that mediates homotypic cell-cell interactions. Intracellularly, RPTPμ consists of a relatively large juxtamembrane region and two phosphatase domains, but little is still known about its substrate(s). Here we show that RPTPμ associates with the catenin p120 ctn , a tyrosine kinase substrate and an interacting partner of cadherins. No interaction is detectable between RPTPμ and β-catenin. Furthermore, we show that tyrosine-phosphorylated p120 ctn is dephosphorylated by RPTPμ both in vitro and in intact cells. Complex formation between RPTPμ and p120 ctn does not require tyrosine phosphorylation of p120 ctn . Mutational analysis reveals that both the juxtamembrane region and the second phosphatase domain of RPTPμ are involved in p120 ctn binding. The RPTPμ-interacting domain of p120 ctn maps to its unique N terminus, a region distinct from the cadherin-interacting domain. A mutant form of p120 ctn that fails to bind cadherins can still associate with RPTPμ. Our findings indicate that RPTPμ interacts with p120 ctn independently of cadherins, and they suggest that this interaction may serve to control the tyrosine phosphorylation state of p120 ctn at sites of cell-cell contact.

Subfields: Molecular Biology

View Paper: https://www.semanticscholar.org/paper/94d47b649509c150682ee8e5c9fbd92604adcffa