Identification of a novel protein tyrosine phosphatase with sequence homology to the cytoskeletal proteins of the band 4.1 family

Abstract

Use of the polymerase chain reaction (PCR) in conjunction with Southern hybridization, using probes corresponding to known phosphatase sequences, resulted in the identification of rat cDNA clones encoding a novel protein tyrosine phosphatase which was termed rPTP2E. The cDNAs comprise 5,543 bp and predict a polypeptide of 1175 amino acids possessing a single catalytic domain at its C-terminus. The N-terminal region of the deduced polypeptide displays high sequence homology to the cytoskeleton-associated proteins of the band 4.1 family. A variant form, termed rPTP2E1, was also identified which contains the catalytic domain only. rPTP2E and rPTP2E1 were expressed in various rat tissues, particularly abundantly in adrenal glands. The catalytic domain of PTP2E was expressed in Escherichia coli and was shown to possess specific protein tyrosine phosphatase activity. The identification of rPTP2E suggests the existence of a subfamily of band 4.1 domain-containing PTPs which may play an important role in signalling pathway and control of cytoskeletal integrity.