Cloning and expression of an inducible lymphoid‐specific, protein tyrosine phosphatase (HePTPase)

Abstract

Tyrosine phosphorylation and dephosphorylating events have been shown to be central to the process of growth regulation and signal transduction. We report here, the identification of a new gene with a tyrosine phosphatase domain (EC 3.1.3.48) which is expressed exclusively in thymus and spleen. A cDNA of 2760 bp encodes a 339‐amino acid, intracellular, single‐domain tyrosine phosphatase. When expressed as a glutathionine‐S‐transferase fusion protein, efficient lysis of p‐nitrophenyl phosphate is noted, indicating in vitro enzymatic activity of the cloned gene product. Normal mouse lymphocytes increase mRNA expression 10‐15‐fold upon stimulation with phytohemagglutinin, concanavalin A, lipo‐polysaccharide or anti‐CD3 monoclonal antibody. This new hematopoietic tyrosine phosphatase, (HePTP), may play a role in the regulation of T and B lymphocyte development and signal transduction.