Michael C. Holmes and Robert Tjian.

Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720.

The TATA-binding protein (TBP) - related factor 1 (TRF1) is expressed in a tissue-restricted fashion during Drosophila embryogenesis and may serve as a promoter-specific recognition factor that can replace TBP in regulating transcription. However, bona fide target promoters that would preferentially respond to TRF1 have remained elusive. Polytene chromosome staining, chromatin immunoprecipitation, direct messenger RNA analysis, and transient co-transfection assays identified the Drosophila gene tudor as containing a TRF1-responsive promoter. Reconstituted in vitro transcription reactions and deoxyribonuclease I footprinting assays confirmed the ability of TRF1 to bind preferentially and direct transcription of the tudor gene from an alternate promoter. Thus, metazoans appear to have evolved gene-selective and tissue-specific components of the core transcription machinery to regulate gene expression.

1. "Long Range Regulation and Insulation of Domains".

2. "Oncogenes as Molecular Targets within Active Chromatin".

3. "Nuclear RNA Species Activate DNA Transcription within Chromatin".

4. "Nuclear Polyanions as De-Repressors of Synthesis of Ribonucleic Acid".

5. "Ultrastructural Continuity Between Active and Repressed Chromatin".