Cloning and expression of human cDNA encoding human homologue of pituitarytumor transforming gene

Recently, a potent transforming gene which was exclusively expressed in rat pituitary tumor but not in normal pituitary had been isolated and named as pituitary tumor transforming gene (PTTG). A cDNA clone encoding human homo logue of rat PTTG was isolated from human fetal liver cDNA library. It cont ained an open reading frame of 603 base pairs predicting a protein composed of 201 amino acids with a calculated molecular weight of 26 kDa. The deduc ed protein showed about 85% homology (78% identity, 7% favored substitution ) with the rat PTTG. Northern blot analysis showed that the cDNA hybridized to 1.0 kb mRNA species which was expressed in fetal liver and several canc er cell lines. These results suggest that the presence of the human homolog ue of rat PTTG gene may not be restricted to pituitary tumor.