Role of the Ada adaptor complex in gene activation by the glucocorticoid receptor.
We have shown that the Ada adaptor complex is important for the gene activation capacity of the glucocorticoid receptor in yeast. The recently isolated human Ada2 protein also increases the potency of the receptor protein in mammalian cells. The Ada pathway is of key significance for the tau1 core transactivation domain (tau1c) of the receptor, which requires Ada for activity in vivo and in vitro. Ada2 can be precipitated from nuclear extracts by a glutathione S-transferase-tau1 fusion protein coupled to agarose beads, and a direct interaction between Ada2 and tau1c can be shown by using purified proteins. This interaction is strongly reduced by a mutation in tau1c that reduces transactivation activity. Mutations affecting the Ada complex do not reverse transcriptional squelching by the tau1 domain, as they do for the VP16 transactivation domain, and thus these powerful acidic activators differ in at least some important aspects of gene activation. Mutations that reduce the activity of the tau1c domain in wild-type yeast strains cause similar reductions in ada mutants that contain little or no Ada activity. Thus, gene activation mechanisms, in addition to the Ada pathway, are involved in the activity of the tau1c domain.
Henriksson
A
A
Department of Biosciences, Karolinska Institute, Novum, Huddinge, Sweden.
Almlöf
T
T
Ford
J
J
McEwan
I J
IJ
Gustafsson
J A
JA
Wright
A P
AP
D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D011494:Protein Kinases / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D013329:Structure-Activity Relationship; D015534:Trans-Activators / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation
C090575:ADA2 protein, S cerevisiae; D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D046911:Macromolecular Substances; C083323:NGG1 protein, S cerevisiae; D011965:Receptors, Glucocorticoid; C099690:SPT20 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C097695:TADA2A protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D011494:Protein Kinases