MOLECULAR-CLONING, CHARACTERIZATION, AND CHROMOSOMAL LOCALIZATION OF A NOVEL PROTEIN-TYROSINE-PHOSPHATASE, HPTP-ETA

Protein-tyrosine phosphatases (PTPases) are considered to play an impo rtant role in signal transduction. We previously identified partial se quences of three novel PTPases in a human leukemic cell line, F-36P. W e describe here cloning, characterization, and chromosomal localizatio n of one of the newly identified PTPases, termed as HPTP eta (human pr otein-tyrosine phosphatase eta) The deduced amino acid sequence was co mposed of an extracellular region homologous to fibronectin type III r epeats, a transmembrane region, and a cytoplasmic region containing a single PTPase-like domain. Based on its primary structure, this clone belongs to type-III receptor-type PTPases. The PTPase-like domain show ed PTPase activity when expressed in Escherichia coli. Antibody agains t the extracellular region detected a protein of 220 to 250 kD in huma n hematopoietic cell lines expressing HPTP eta mRNA. The antibody also recognized a protein of approximately the same molecular weight in CO S cells transfected with HPTP eta cDNA, indicating that the antibody s pecifically recognized HPTP eta gene product and that the cloned cDNA contained full-length coding region, The chromosomal localization dete rmined by fluorescence in situ hybridization showed that the HPTP eta gene was located at chromosome 11p11.2 on the short arm of chromosome 11, which is frequently lost or deleted in human carcinomas. (C) 1994 by The American Society of Hematology.