RECEPTOR PROTEIN-TYROSINE PHOSPHATASES - INVOLVEMENT IN CELL-CELL INTERACTION AND SIGNALING

Receptor protein tyrosine phosphatases (RPTPs) represent a relatively new family of cell-surface receptors consisting of a variable, putativ e ligand-binding ectodomain followed by a single transmembrane segment and one or two intracellular catalytic domains. The RPTPs are thought to transduce extracellular signals by dephosphorylating tyrosine-phos phorylated intracellular substrate. As such, they are the enzymatic co unterparts of the well studied receptor tyrosine kinases. However, lit tle is known about the signaling mechanisms and biological functions o f the RPTPs. Recent studies show that the extracellular domain of cert ain RPTPs can mediate either hemophilic or heterophilic interactions a nd suggest a role in cadherin-mediated cell-cell adhesion, possibly vi a an action on catenins. This review will focus on the role of RPTPs i n cell-cell interaction and the possible biological implications.