Characterization of the adhesive properties of the type IIb subfamily of RPTPs

摘要

Receptor protein tyrosine phosphatases (RPTPs) have cell adhesion molecule-like extracellular domains coupled to cytoplasmic tyrosine phosphatase domains. PTPmu is the prototypical member of the type IIb subfamily of RPTPs, which includes PTP rho, PTP kappa, and PCP-2. We performed the first comprehensive analysis of the subfamily in one system, examining adhesion and antibody recognition. We evaluated if antibodies that we developed to detect PTPmu also recognized other subfamily members. Notably, each antibody recognizes distinct subsets of type IIb RPTPs. PTPmu, PTP rho and PTP kappa have all been shown to mediate cell-cell aggregation, and prior work with PCP-2 indicated that it can mediate bead aggregation in vitro. This study reveals that PCP-2 is unique among the type IIb RPTPs in that it does not mediate cell-cell aggregation via homophilic binding. We conclude from these experiments that PCP-2 is likely to have a distinct biological function other than cell-cell aggregation.