Cloning and Expression of Chicken Protein Tyrosine Phosphatase Gamma

A 5,403 bp cDNA encoding chicken protein tyrosine phosphatase gamma (PTPgamma) was isolated and sequenced. The predicted open reading frame of 1,422 amino acids (aa) includes 742 aa of extracellular (EC) domain, 26 aa of transmembrane (TM) domain and 634 aa of intracellular domain. The chicken PTPgamma has a 86.7% aa identity to its human homolog and contains the carbonic anhydrase-like domain and fibronectin type III homologous regions in the EC domain, as well as the tandem linked catalytic sequences in the cytoplasmic domain. However, the chicken PTPgamma lacks 29 aa immediate downstream of the putative TM domain in comparison with its human counterpart. Northern analysis revealed the presence of two transcripts of 6.3 and 9.5 kb in various tissues. The cytoplasmic domain of the PTPgamma could be expressed as an enzymatically active form in SF9 insect cells. PTPgamma could also be expressed in normal and rsc-transformed NIH3T3 and Rat 1 cells as a gag-PTP fusion protein, but no detectable effects on growth and colony formation of these cells were observed. Copyright 1996 S. Karger AG, Basel