ABSTRACT
CPTP1 is a nontransmembrane chicken protein tyrosine phosphatase having 92% sequence homology to the corresponding 321 amino acids of human protein tyrosine phosphatase 1B (HPTP1B). Using anti-CPTP1 antibody, we identified CPTP1-like rat PTP1 of 51 kappa Da in Rat-1 and v-src-transformed Rat-1 fibroblasts. Here we show that CPTP1-like rat PTP1 binds to p60v-src in vivo and CPTP1 also can associate with p60v-src in cell lysate of v-src- transformed Rat-1 fibroblasts. Interaction between HPTP1B-type PTPs, CPTP1-like rat PTP1 and CPTP1, and p60v-src was reduced by vanadate treatment for 13 h due to down regulation of the protein level of p60v-src in vivo. Interestingly, CPTP1-like rat PTP1 was coimmunoprecipitated with a 70-kappa Da protein which has a possibility to be tyrosine- phosphorylated by p60v-src in v-src-transformed Rat- 1 fibroblasts. These results suggest that HPTP1B- type PTPs may play an important role in p60src dependent signal pathway in eucaryotic cells.