摘要：

THE zinc-finger protein Krüppel (Kr)1 is an integral part of the Drosophila segmentation gene cascade2 and is essential in organo-genesis during later embryonic development3. In tissue culture, Kr regulates transcription4–9. Monomeric Kr can act as a transcrip-tional activator, whereas Kr dimers formed at high concentrations cause repression6. Here we show that Kr-dependent control of transcription involves functional interactions with components of the basal RNA polymerase II transcription machinery, which includes the initiation factors TFIIA, B, E, F, H and I (refs 10,11) as well as the TATA-binding protein (TBP) and TBP-associated factors (TAFs) contained in the multisubunit TFIID (ref. 12). Our results indicate that when acting from a site close to a basal promoter, monomeric Kr interacts with TFIIB to activate transcription, whereas an interaction of the Kr dimer with TFIIEβ, a subunit of TFIIE, results in transcriptional repression.

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