HPTTG, A HUMAN HOMOLOG OF RAT PTTG, IS OVEREXPRESSED IN HEMATOPOIETICNEOPLASMS - EVIDENCE FOR A TRANSCRIPTIONAL ACTIVATION FUNCTION OF HPTTG

We have isolated a human cDNA clone encoding a novel protein of 22 kDa that is a human counterpart of the rat oncoprotein PTTG. We show that the corresponding gene (hpttg) is overexpressed in Jurkat cells (a hu man T lymphoma cell line) and in samples from patients with different kinds of hematopoietic malignancies. Analysis of the sequence showed t hat hPTTG has an aminoterminal basic domain and a carboxyl-terminal! a cidic domain, and that it is a proline-rich protein with several putat ive SH3-binding sites, Subcellular fractionation studies show that, al though hPTTG is mainly a cytosolic protein, it is partially localized in the nucleus. In addition we demonstrate that the acidic carboxyl-te rminal region of hPTTG acts as a transactivation domain when fused to a heterologous DNA binding domain, both in yeast and in mammalian cell s.