RN-TRE SPECIFICALLY BINDS TO THE SH3 DOMAIN OF EPS8 WITH HIGH-AFFINITY AND CONFERS GROWTH ADVANTAGE TO NIH3T3 UPON CARBOXY-TERMINAL TRUNCATION

We isolated a cDNA encoding a protein, RN-tre, which shows homology to the N-terminus of the tre oncogene product and has SH3-binding abilit y as well as an evolutionarily conserved domain, termed TrH, with prot ein-binding ability in vitro, In the present study, we identify the pr oduct of the RN-tre gene as a 97 - 100 kDa protein, We demonstrate sta ble association in vivo and ill vitro between RN-tre and eps8, mediate d by the SH3 domain of the latter, In vitro, RN-tre displayed remarkab le preference for binding to the eps8-SH3, as compared to eight other SH3s. The Kd for the in vitro interaction between RN-tre and eps8-SH3 was between 10(-8) and 10(-7) M, A role for RN-tre in cell proliferati on was suggested by the finding that a C-terminal truncated mutant was able to confer proliferative advantage and reduced serum-requirement to NIH3T3 fibroblasts, Finally, comparison of the structure and biolog ical activities of RN-tre and of the tre oncogene product, provided in sight into the mechanism of oncogenic activation of tre.