Related Experiment Video
Updated: Jun 20, 2026

TRAP-rc, Translating Ribosome Affinity Purification from Rare Cell Populations of Drosophila Embryos
Published on: September 10, 2015
Transcriptional activation and repression by Ultrabithorax proteins in cultured Drosophila cells
M A Krasnow1, E E Saffman, K Kornfeld
1Department of Biochemistry, Stanford University, CA 94305.
Abstract:
Homeotic genes of Drosophila melanogaster such as Ultrabithorax (Ubx) and Antennapedia (Antp) have long been thought to select metameric identity during development by controlling the expression of various target genes. Here we describe a cotransfection assay in cultured D. melanogaster cells that is used to demonstrate that Ubx proteins (UBX) can repress an Antp promoter fusion and activate a Ubx promoter fusion, activities predicted from genetic studies. We show (a) that UBX proteins regulated the level of accurately initiated Antp P1 and Ubx transcripts, (b) that activation of the Ubx promoter required a downstream cluster of UBX binding sites, and (c) that binding site sequences were sufficient to confer regulation on a heterologous promoter, regardless of their orientation or precise position. We conclude that UBX proteins are transcriptional repressors and activators, and that their actions are mediated by binding to promoter region sequences. Each member of the UBX protein family has similar regulatory abilities, but the properties of synthetic mutant forms suggest that UBX proteins may have a modular design similar to other transcriptional regulators.
More Related Videos
Related Concept Videos
RNA Polymerase II Accessory Proteins
Co-activators and Co-repressors
Eukaryotic Transcription Activators
The binding domains are capable of recognizing and interacting with regulatory sequences on the DNA. These domains are...
Eukaryotic Transcription Inhibitors
Eukaryotic transcription inhibitors usually contain two distinct domains, a DNA...
Master Transcription Regulators
The Ratio of X Chromosome to Autosomes
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...

