The ability to transfer genes between mammalian cells, viruses and yeast has allowed the powerful yeast genetic procedures to be applied to both mammalian and viral genes. To study the function of mammalian and viral genes, fission yeast Schizosaccharomyces pombe replicating vectors were developed which can be shuttled between different eukaryotic organisms. These vectors can be used for isolating cDNA clones from libraries encoding cellular factors required for transcription of the eukaryotic promoters. A sequence within the HIV-1 LTR promoter corresponding to the NFkB regulatory element has been shown to be functional in S. be. However, the HIV-TAT protein did not trans-activate the HIV-LTR promoter, suggesting the S. pombe lacks a factor required for such a trans-activation.
