Protein tyrosine phosphatase ζ/RPTPβ interacts with PSD-95/SAP90 family

PTP zeta/RPTP beta is a proteoglycan-type receptor-like protein tyrosine phosphatase specifically expressed in the brain. Although several ligands of PTP zeta have been identified, proteins interacting with the intracellular region of PTP zeta are still unknown. We performed yeast two-hybrid screening using the intracellular region of PTP zeta as a bait, and found that the C-terminal sequence of PTP zeta binds to the PSD-95/SAP90 family through the second PDZ domain. Immunohistochemical analysis revealed that PTP zeta and PSD-95/SAP90 are similarly distributed in the dendrites of pyramidal neurons of the hippocampus and neocortex. Furthermore, subcellular fractionation experiments indicated that PTPS is concentrated in the postsynaptic density fraction. These results suggested that PTPS is involved in the regulation of synaptic function as postsynaptic macromolecular complexes with PSD-95/SAP90. (C) 1999 Elsevier Science B.V. All rights reserved.