Vergleichende Charakterisierung der Transkriptionsaktivatoren Ino2 und Ino4 der Hefen Saccharomyces cerevisiae und Candida albicans In S. cerevisiae structural genes of phospholipid biosynthesis are activated by an UAS element designated ICRE (inositol choline responsive element). This sequence motif is recognized by a heterodimer containing transcriptional activator proteins Ino2 and Ino4 both bHLH proteins. Ino2 activates transcription via two transcriptional activation domains (TADs) while Ino4 is necessary for nuclear import. Opi1 acts as a negative regulator binding to Ino2 via its repressor interaction domain (RID). SUA7 encodes the basal transcription factor TFIIB in S. cerevisiae and is recruited to promoters by interaction with Ino2. In this work strategies were investigated to purify a heterologously expressed Ino2 Ino4 heterodimer by chromatographic methods. Development of an affinity based strategy allows separating epitope tagged Ino2 and Ino4 from other proteins in cell lysates. After further up scaling for larger cell amounts it should now be possible to purify an Ino2 Ino4 heterodimer and make it available for X ray structural analysis after crystallization. Using S. cerevisiae genomic sequence data bases it was possible to identify ICRE containing promoter regions of structural genes that do not play an apparent role in phospholipid biosynthesis. It was shown that ICRE containing genes ARG4 ERG20 GPD2 and VHT1 were regulated moderately by IC while FAR8 RSF1 YEL073c and URA8 were regulated much stronger... Genregulation Promotor <Genetik> Repression <Genetik> Derepression Saccharomyces Gene regulation Inositol Choline Phospholipid biosynthesis cerevisiae Candida albicans