Isolation of a Yeast Gene Encoding a Protein Homologous to the Human Tat-Binding Protein TBP-1

We have cloned a putative yeast homolog of the gene encoding the human Tat-binding protein, TBP-1. The gene termed TBPY encodes a 45,243-dalton protein displaying a heptad repeat of hydrophobic amino acids reminiscent of a leucine zipper. Secondary structure predictions suggest the possibility of formation of an amphipathic helix that could further be organized into a coiled-coil. Additionally, the protein product of TBPY shows amino acid signatures characteristic of a large family of RNA and DNA helicases. We propose that the hydrophobic region of yTBP-1 participates in self-dimerization or heterodimerization.