A DNA fragment XPXX of 240 b.p. was isolated at random from the genomic sequences of S. cerevisiae by using a plasmid that contained a promoterless reporter gene lacZ of E. coli. XPXX was capable of activating synthesis of three reporter genes (pho5 from yeast and bacterial lacZ and neo) in yeast cells bidirectionally. Results of Southern-blot hybridization with yeast genomic DNA suggest that the cloned sequence is represented in at least ten copies per cell. Nucleotide sequence of XPXX shows that DNA contains putative TATA elements and four tandems of inverted repeats: [sequence: see text].