THE GLUTAMINE-RICH ACTIVATION DOMAINS OF HUMAN SP1 DO NOT STIMULATE TRANSCRIPTION IN SACCHAROMYCES-CEREVISIAE

Eukaryotic transcriptional activators have been classified on the basi s of the characteristics of their activation domains. Acidic activatio n domains, such as those in the yeast GAL4 or GCN4 proteins and the he rpes simplex virus activator VP16, stimulate RNA polymerase II transcr iption when introduced into a variety of eukaryotic cells, This specie s interchangeability demonstrates that the mechanism by which acidic a ctivation domains function is highly conserved in the eukaryotic kingd om. To determine whether such a conservation of function exists for a different class of activation domain, we have tested whether the gluta mine-rich activation domains of the human transcriptional activator Sp 1 function in the yeast Saccharomyces cerevisiae. We report here that the glutamine-rich domains of Sp1 do not stimulate transcription in S. cerevisiae, even when accompanied by human TATA-box binding protein ( TBP) or human-yeast TATA-box binding protein hybrids. Thus, in contras t to the case for acidic activation domains, the mechanism by which gl utamine-rich domains stimulate transcription is not conserved between S. cerevisiae and humans.