FUNCTIONAL DIFFERENCES BETWEEN MAMMALIAN TRANSCRIPTION ACTIVATION DOMAINS AT THE YEAST GAL1 PROMOTER

We have fused representatives of three structurally and functionally d istinct classes of mammalian transcription activation domains for RNA polymerase II to the yeast GAL4 DNA binding domain. All fusion protein s were stable when expressed in yeast and were tested for their abilit y to activate transcription from various positions in the yeast GAL1 p romoter. Activation domains functional from remote as well as TATA-pro ximal positions in mammalian cells, e.g. the acidic-type domain of VP1 6, also stimulate transcription in yeast from various promoter positio ns. Proline-rich domains, as e.g. in AP-2 and CTF/NF1, with considerab le promoter activity and low enhancer activity in mammalian cells stim ulate transcription in yeast only from a position close to the TATA bo x. The glutamine-rich domains of Oct1, Oct2 and Spl, which activate tr anscription in mammalian cells from close to the TATA box in response to a remote enhancer, are inactive in the yeast GAL1 promoter. This fi nding might reflect some basic difference between the organization of yeast and mammalian promoters.