Molecular cloning and expresion of a protein‐tyrosine phosphatase showing homology with transcription factors Fos and Jun

Abstract

A cDNA clone coding for a protein‐tyrosine phosphatase (PTPase) was isolated from a rat spleen cDNA library. Nucleotide sequence of the clone showed an open reading frame coding for a polypeptide of 363 amino acids. Expression of this clone in E. coli in an expression vector showed PTPase activity. The non‐catalytic region of this PTPase located at the carboxy terminus shows homology with the basic domains of transcription factors Fos and Jun. Northern blot analysis showed that a 1.7 kb transcript was present in many tissues and cells, the highest level being in macrophages. This PTPase is a rat homolog of human T‐cell PTPase although it shows 3 large deletions in the carboxy terminal non‐catalytic region.