The association of transcribed genes with the nuclear matrix of Drosophila cells during heat shock

Using the transcriptionai modulation afforded by heat shock, we found that the association of active genes with the nuclear matrix was not dependent on their level of transcription. Heat shock genes were matrix associated both before heat shock (when transcription was relatively low), and during heat shock (when transcription was greatly increased). Conversely, the cytoplasmlc actin gene was matrix associated during normal growth conditions (when transcription was high) and during heat shock (when transcription was greatly decreased). Removal of greater than 99.7% of nascent RNA during preparation of the matrices did not affect these findings. Detailed examination of the cytoplasmlc actin gene revealed that its matrix association was apparently mediated by multiple interactions near the 5′ end of the gene.